'89 CRX HF + D15Z1 troubleshooting...
 

I recently test drove my project and a few issues arose. She idles fine but when revving in neutral she hesitates/stumbles below 3k and also has severe rev hang (takes several seconds to return to idle speed, stumbles on the way down too). On the road it's similar with heavy hesitation/intermittent power delivery below 3k and sometimes beyond. It feels like she bucks to get up to speed and that translates into the shifter. I understand this engine is gutless below VTEC/lean burn but VTEC engages approx. at 2200 RPM in these cars, and the hesitation lasts beyond that. Below are specs (engine is stock unless otherwise noted):

- P07 ECU (stock for this engine)
- Rywire OBD-0-1 conversion harness w/ resistor box delete and OBD-1 injectors (stock Z1)
- NO CELS
- stock exhaust, no muffler
- used stock 5-wire O2, how do I check voltage w/ a DMM?
- drained fuel tank, fresh 87 octane
- new fuel filter
- new NGK plug wires
- correct spark plugs
- cap, rotor, button look fine
- Cooling fan doesn't work since I deleted A/C but she doesn't overheat w/ the stock HF radiator, toggle switch for hot days
- DIY engine grounding kit
- DIY polyurethane motor/tranny mounts, slightly stiffer than stock
- Timing adjusted to spec
- Correct PCV valve installed

If there's anything else I'll update, Thanks, Mak

I am stoked to see your thread!!! Check out my new thread in How to do it yourself . . . just in today. If you read the paragraph on transmission you may find the answer to your problem. I sure hope so. If you know of any way to use the HF transmission with the VSS please let me know.

There should be an ignition timing connector located under the passenger side of the dashboard. It is a 2 pin connector, with wire colors BRN and GRN/WHT. Jumper these two wires to set timing.

Setting timing will probably go a long way towards fixing your hesitation problem.

also, my vx has a fairly bad low throttle hesitation. I think it is related to it coming out of the lean burn mode, but I am not sure. It got a lot better after setting the timing, but it is still there. I am in the process of getting a new fuel filter, and having some injectors cleaned and flow tested. I am hoping this will eliminate the hesitation, but it seems like this is a problem that I hear about with the vx a lot, so it might just be the nature of the motor.

Actually, '88-89 models have the service connector by the driver's side engine mount.

Mak, how can you tell you don't have any CELs if you haven't jumped the service connector?

Good call. I could vaugely remember that there was something different between the different crx years, but all I had to look at was a 1991 civic manual.

When he says he doesn't have any CELs, he probably just means the light isn't on. It is true though, that he probably needs to jumper the connector and see if there are any codes that wouldnt trigger a check engine light.

True, I don't have a steady CEL. Also, when I swapped the Rywire harness in, the instructions indicate which wire does what. At the very end they indicate the blue wire that is on the custom pigtail portion of the harness to be grounded to check for codes. Since I didn't have a CEL and was skeptical I had everything wired correctly having never done a swap before, I intentionally unplugged the VTEC pressure switch and ran the car at idle. The CEL popped up, I grounded the blue wire, and sure enough code 22 flashed (VTEC psi switch error). This new blue wire is now my service connector, as per Paul of Rywire informed me. Mak

***UPDATE 3/22***

After 10 hours today, changed the timing belt, water pump, tensioner and spring (All Honda Genuine parts) and even set valve lash while I was there. Got the crank/cam/ignition timing spot on, but the problem still exists, but the rev pickup is improved. When in fast idle the car is possessed, it surges and falls, fluctuates, etc but ultimately stays above 1.5-2k. After it warms up, the idle settles to 7-800 rpm and it purrs like a walrus (kitten + no muffler). What gives? Also, throttle input on both cold and warm idle causes random events such as rev hang, rough idle, and when cold, surging. Guess I'm not out of the woods yet on this Z1...could it be a MAP or TPS? EGR? Other acronyms? HELP! Mak

- Clean the IACV. Spray carb cleaner down the inlet port in the throttle body until the engine stalls. Let it soak for 15 mins and restart it. Spray 5-10 bursts of cleaner down the port so the engine bogs down but doesn't stall. Repeat until you feel satisfied that it's clean, you run out of carb cleaner, or the fumes get to you.

- Check for vacuum leaks. Spray carb cleaner on various hoses, seals and such in the engine bay, listening for changes in the idle (bogging, stuttering and such). Try pinching off each vacuum hose one at a time at the manifold... If the idle drops, that hose or component is leaking.

- Check the TPS. Pick up a digital multi-meter if you don't already have one. A model with a bar graph helps. Scrape enough insulation off the grn/wht (green with a white stripe) and red/blu wires to make a good electrical connection with the meter. Switch the ignition on and measure the voltage across the wires (grn/wht negative, red/blu positive). You should see between .45 and .5 volts with the throttle closed, and around 4.5 volts with it fully open. You should see a smooth (no voltage spikes - this is where the bar graph comes in handy) transition between the two as you slowly open and close the throttle.

- Unbolt the EGR valve and see if the ports look clogged or the valve looks worn or damaged. If you have a vacuum pump, check that the valve moves smoothly and isn't leaking. Go ahead and soak the ports down with carb cleaner while you're in there.

- Hit it with a brick.

Thanks bobski, I'll attempt them all next week. I have a standard Digital MM, no graphs. I also searched similar complaints and will attempt to test my fuel pump and distributor igniter, but I'll go easiest ---> difficult and see what happens. Thanks, Mak

P.S. Before I try the brick method, I'll get a short video of the idle in action because diagnosing cars using text is difficult.

The ignitor typically manifests itself as RPM-dependant stuttering and missing and/or a bouncing tach, but it wouldn't hurt. How are you going to test the pump? A pressure gauge?

Sounds good. :)
I'll be at my dad's in Mocksville next week if you want another set of eyes and ears.

It sounds to me like it could be a TPS and/or ignitor issue.

Good luck getting it resolved!

*** UPDATE *** 3/28

Here's what I got through so far:

I used MAF/Sensor cleaner to bog/soak the intake b/c all the carb cleaners I read were not recommended for fuel injected and left a residue, the MAF spray didn't. Still bogged/stalled the engine when sprayed though.

Sprayed carb cleaner on all fittings/hoses, no leaks to be heard. Pinched every hose I could find and the only one to lower the idle was the PCV hose between the valve and the Intake Manifold. Is this normal?

TPS has .5-4.5v range depending on angle, no big spikes in range while operating the plate by hand = OK. Also has 5v supply = OK.

Could not get the EGR off due to a stripped bolt so I tested it w/ vacuum and DMM. The EGR Control Solenoid Valve (in the black box) has 12v supply = OK. There was no vacuum between EGR and black box = OK. When I applied 8mm Hg vacuum to EGR it stalled the engine = OK. When I jumped the connector on the black box to have 12v the vacuum shot up quick = OK. The only discrepancy was the EGR connector only had 2.85v supply when the ignition was on, engine off, instead of the recommended 5v, leading me to believe there is a problem down the line on the yel/wht wire. Rywire instructed me to tap the MAP 5v supply back when I was converting to ODB1 so that's my first avenue for next week. BTW, the MAP has 5v = OK. I swapped in a spare P05 ECU and the EGR still only had 2.85v.

I've included a short video of the warm idle at the end of my precedings, I didn't really change anything so why the rev hang, decel sputter, and accel surge are gone is anyone's guess. I have a feeling it will return until I track down the source. I didn't have time to test the distributor nor did I have a fuel pressure gauge to test that system so I still have a few options. Keep the suggestions coming, I wish I had taped some of the issues before I started. Mak

Video -------> https://youtube.com/watch?v=-63J1nXoLVM

(It idles fine then I jab it a bit, no noted fluctuations...for now. Next time I'll only shoot a video if she acts up and I'll include a sustained rev shot.)

So the check engine light is on, but it doesn't display any codes when you jump the service connector, right? Try unplugging various engine sensors one at a time and see if the CEL will turn off. I seem to recall reading something about the light coming on like that if certain sensors or wires are shorted out. The low voltage on the EGR supply would seem to point in that direction as well.

I'll go check the PCV valve idle thing on my 'Z6, but I don't think it's supposed to make much of a difference idle-wise.

Alright... Pinching off and re-opening the vacuum line between the valve and manifold made about an 80 rpm difference (760 down to 680, or up to 840), but the ECU compensated within a second or two.

Oh, I forgot to mention I have No CEL, except when the VTEC Pressure Sensor connector backs out from time to time (the plastic is cracked). The voltage issue with the EGR apparently isn't enough to through a code. Where in the engine bay is a good 5v source (besides MAP sensor?) Next time I'll re-splice and tap the EGR to see if that clears it up. Mak

Uh, that sounds exactly like an ECU that's in backup mode. I bet you have a bad ECU or you wired something wrong.

When chipping an ECU and you screw up (like me), the ECU fails to boot and then the engine will sorta run. Like not reving past 4k, poor response, higher idle, slow return to idle. The CE will stay on.

Try another ECU.

I tried another ECU, a P05, and the voltage came out the same. The P07 I'm currently running was bought of a member from here, and he said it was never tampered with. so it should be fine. Also, after probing all of the MAP wires, the yel/wht is half the needed voltage, or 2.5v. The EGR is tapped into this wire, also with 2.5v plugged in, and when both are unplugged, it registers 3.6v for both at their respective connectors. Rywire instructed me to tap this particular MAP wire b/c it supplies 5v. Why is it splitting the voltage? And where else is there a constant 5v in the engine bay? Oh, and still no CEL but I haven't run the car with the sensors unplugged, just w/ ignition power, engine off. Mak

Unplug your ECU, MAP, EGR and TPS sensors. Test the resistance between ground and each pin of the sensor connectors. Test the resistance between the pins at each connector. You should see no connection (off the scale resistance) in each case.

Finally, Finally, found the problem! Seems Rywire instructions had me tap the wrong wire, thus causing the EGR to have fluctuating voltage and a crazy idle and rev decel. It now has 5 volts. What a simple fix it was. Anyway, with that out of the way, an 8 mile test drive ensued and I noticed a few other things:

- Throttle (as in gas pedal/TB plate) still sticks randomly, have to 'jab' the pedal to get it release
- Has a tendency to stutter/jerk/hop at low speeds in low gear
- Has a tendency to do the same at sustained speeds, barely noticeable, usually low RPMs again (below 3k).
- noticeable vibration through the shifter, might have to do w/ harder polyurethane mounts on engine and bushings in shifter being stiffer
- still can't tell if VTEC is engaging, I try to feel for it around 2-2.5k but I second guess myself
- slight gas smell after driving inside car, smell strongest behind driver's seat and next to gas door (only at 1/3 tank if you were wondering)
- NO CEL yay!

So I still have a few issues but my electrical gremlins have been vanquished! Thanks to all who helped out w/ that one....Mak

That's not good. I would fiddle with the gas pedal while stopped, with the engine off and try to get it to stick. If it sticks, you can fiddle with the various components (throttle pulley, throttle cable, pedal assembly) to figure out which one is sticking.
My bet would be on the cable, then the pedal cluster.

I think some VX ECUs had an output for an economy indicator light in the gauge cluster? Some, maybe all HFs had a similar upshift indicator... Hook 'em up.

The fuel filler pipe is back there. I would pull out the cargo box and maybe the driver's side panel to get a good look at the pipe. Someone may have driven a screw through the pipe to mount an amp or something in the past.
Another possibility is that the top of your gas tank has rusted through in a spot, and is letting vapors out. Maybe the vapors leak in through a torn gasket or something?

All good suggestions. I'll address each one, although I won't get to the car again til next week sometime.

1. I know when I rev the car at the throttle body itself w/ my hand it can still stick, so my guess is cable also, followed by butterfly plate/spring. Time for some WD-40.

2. I remember the Rywire instructions mentioning an upshift light connection w/ the supplied pigtail, I'll just have to track down the original HF one (if it has one, not sure off hand) or rig an LED somewhere.

3. As far as I know this car has little/no rust anywhere. I bought the car despite it's poor mechanical shape because of this quality. My guess is an old fitting/hose/gasket has met it's service limit or as you mentioned, an errant screw tip. I'll let you know when I've cured a few of these. Thanks again, Mak

Back for an update....**edited for clarity**

- fixed the throttle stick, must be in the TB itself, I useda screw as a stopper on the throttle linkage/TB right before it sticks closed.

- the smell hasn't returned but I haven't driven it yet, just cranked/idled for 5 minutes or so.

- Hooked up "economy" aka shift light, VTEC engaged light, and clutch switch (dunno what for, my HF won't start w/o the clutch in anyway). So as I'm attempting to test drive and test all my new hookups, the car won't start :( She turns over fine but I couldn't hear the fuel pump so I did the jumper to main relay test and I have 12v at the connector to the pump/sender. I then hook up a 12v battery to the pump connector itself and I could definitely hear some pump action. I hook it all back up, and...nothing. Why would the pump work w/ direct 12v but not normally w/ a verified 12v coming to the connector? Mak


PS -- after making the pump run on straight battery, the car did crank/run for a few seconds til the gas went out of the line so air/spark are not of concern.

So you have 12V+ and a good ground connection at the connector under the cargo organizer box, but no pumping going on? That says to me that the gas tank wiring harness is screwed up.
What exactly do you mean by connecting power to the pump itself?
Try rigging something up so you can test the voltage to the fuel pump at the cargo bin connector while the connector is still hooked up. It's possible something is damaged in the car wiring or the main relay in such a way that it's creating high resistance. If there's no load on the damaged conductor (as is the case when the connector is unplugged), you wouldn't see a voltage drop, but at the same time the resistance wouldn't allow enough current to pass to run the fuel pump.

To clarify I hooked up a 12v lawn mower battery to the cargo connector and something definitely kicked on in the tank, come to think of it, all those times I test-ran the car or test drove it the pump wasn't loud at all, had to have an assistant to listen in the refiller pipe. The fuel pump in my '85 CRX Si is LOUD. I hear it kick on and prime, and also while running. I even hear the whirr noise fluctuate when I have a blinker on (especially while idling at a stop light, etc). The HF, not so much. I'll try testing it w/ everything hooked up like I did the TPS. Thanks Bobski, you are my best suggester :) Mak

ok, so here goes:

1. I got the car to run, but my fuel pump kill switch seems to be too good at it's job. I fully tested the main relay, another spare relay, both fine. I jumped the fuel pump to run w/ ignition on, no problem, can hear it fine. It seems when I manipulate the kill switch (which is upstream of the main relay) it sometimes interferes with the signal to the fuel pump relay and has to be "reset", usually by turning off the kill switch (no power to pump), removing the key in the ignition completely, then turning the kill switch to the "ON" position (and thus power to pump), then reinserting the key and starting the car. This convoluted method works 90% of the time. The other 10% I disconnect the negative battery cable for a few seconds then repeat the above process with mostly success. If/when I get the car to fire (and the pump is audibly primed beforehand) the car never cuts off unless I remove the key like normal or cue the kill switch. The kill switch is a simple lighted rocker and I've decided to upgrade to a true relay activated, um, relay switch. This should clear up my starting issues. Same goes for the push button start, although I've never had a problem yet from it.

2. The throttle still sticks shut, I've determined its not the throttle plate or the spring/cable, it must be the shaft that it rotates w/ or even a sticky TPS. Oh well, I adapted a machine screw to stop the cable/spring from hitting rock bottom and it has worked so far, although it seems to slowly back out.

3. I also blew several LEDs up testing my VTEC engagement light, all the LEDs tested were spares w/o voltage readings and apparently none could handle 12v. My MM confirmed that w/ the front wheels off the ground, w/ the car in 1st or 2nd, and the temp. gauge a little off "C", my VTEC engages at 3.5k RPM. I suspect on the road the engagement will be at the lower 2.5k but w/o load my test set the bar higher and MAP vacuum wasn't strong enough at 2.5k.

4. Shift light works! Also noticed on the VTEC tests the light kicks on once at a low, slow, RPM shift point and again briefly up past 3k. Odd. Also cut the clutch switch that I just hooked up b/c the HF already had a functioning one somehow. No CEL, oh well.

Once I re-wire and relay the kill switches I may be able to take the beast out for an alignment and that much closer to a DD. With all my electrical issues lately I will also invest in a mini-fire extinguisher. I don't need 2.5 years of tediously slow progress going up in flames b/c of some errant ground or short. AD

PS. Sorry this has become a build thread of late. Comments welcome, however.

Oh, don't be sorry this has become a build thread! It's got at current 789 views and counting! Popular threads are popular threads, and it happens to be one of my favorites, too. Keep us all posted. I'm very interested as I would like to eventually put a more powerful and efficient engine in my CRX too.

It's long overdue update time...

The Project FrakenRex (Think Kraken) is road legal, aligned, and one solid color! She has been driven approx. 120 miles over the past few months, usually one day a week for city/errands b/c there are still some engine issues to deal with that are keeping her from DD duty. The number one issue is an odd occurrence of what I call ICB, or Irritating Cruise Buck (not intercontinental Ballistic Missle). Under throttle, hitting VTEC, light cruise, etc she is pretty smooth, but say I achieve 30, 55, 0r even 70 mph and then let off the throttle completely and coast in gear to a stop light/down hill, etc. Only during this no throttle coast (in gear) does the car irritatingly jerk, buck, surge and fall, etc (the severity is very high in 1st gear, and lessens as the gears increase, but in 5th @ 70 it's still very noticeable). To the driver behind me it probably looks as if I am getting a first lesson on driving stick. Any suggestions? See the first post for a mechanical backstory. I'll post new pics eventually. Thanks, Mak

The engine shouldn't be able to do anything to cause bucking during a no-throttle coast - the fuel injectors shouldn't be firing. Make sure the throttle cable isn't too tight (and holding the throttle open slightly), then check the TPS voltage when the throttle is fully closed... It should be between 0.45 and 0.5 volts.

I tested the TPS, .42 closed, 4.5-4.8 open. The throttle plate continued to stick closed so I took the TB off and gave it a good cleaning. The plate STILL sticks and I've resorted to sanding the high spots w/ 2000 grit sandpaper. I could really use a spare TB to help rule out this possible cause, either the sticking or iffy TPS. Also, there were not any voltage spikes when continually opening/closing the plate. What else? IACV? ECU?

Mine used to do this. The ultimate fix was new o2 sensor but the proper spark plugs also helped.

There should be a allen screw/locknut combo that the throttle cable pulley stops against... It sets the closed point. Both the sticking and the low voltage say it's been tampered with. If the throttle closes too far, the plate runs into the throttle body wall and gets wedged there, thus the sticking.

bobski to the rescue again! I sourced a replacement stop screw at the local U-pull-it and now it finally doesn't get stuck. Simple fix. I just hope the sanding on the plate didn't create a gap b/w the plate and TB wall to let air through during idle. I held the assembled TB up the light and could see a faint ring of light, similar to a complete solar eclipse, but it's not a substantial gap. The piece is certainly clean though w/ multiple sprays of carb cleaner and a 2000 grit rub down. I'll be able to put the TB back on the car tomorrow and then adjust the stop screw using the MM to set a .45-.5 spec idle voltage. Hopefully this will clear up my throttle stick and no input cruise bucking so she can be road worthy for a DD. I'll let you know how it and the subsequent test drive goes. Thanks, Mak

It sounds like some sorta vacuum leak.....

After replacing the TB (and set closing voltage at .48) and taking her on a 7-mile test drive, the stick problem is gone but the irratic idle, cruise buck surge crap still persists. I may need to check vacuum at the MAP to make sure no air gets past the plate under no throttle input. Slurp, I will try to locate a vacuum leak elsewhere w/ carb cleaner method (I've done this before w/ no luck). I noticed my upshift light is quirky, coming on twice when I steadily accelerate, once in rather low RPM and again before VTEC kicks in (as indicated by my custom amber LED dash light) In cruise/buck mode the light sometimes flickers, other times doesn't even come on. I've noticed the buck problem isn't 100% consistent, sometimes allowing me to cruise all the way down to below 1k RPM, but 70-85% of the time it'll buck/surge/irritate me before it makes it that far. How would I go about testing the O2 sensor? Next time I'll try and get video of the crappy idle and/or cruise buck, which may be harder to make noticeable on video. Mak

I've ordered a spare P07 ECU to try and rule out a faulty ECU, and to have a spare in the future. I'm leaning towards an obscure vaccuum leak, probably from some 15-year old o-ring or maybe my doomed TB. Mak

ok, cleaned IACV (altho it didn't turn out to be very dirty) and drove the car it's longest distance since the swap (85 miles). The jerking is less noticeable but the idle is randomly off, often surging (but not necessarily rise and fall, as is typical for D-series Hondas) but a steady surge at a stoplight to 2 or even 3k. Also, when upshifting w/ no throttle input, the revs actually rise too between shifts enough to notice. Vac leak? I'm checking injectors next per molecule's suggestion, then I may have to find a spare O2 to troubleshoot that expensive fix. Mak

P.S. oh, and I definitely feel the hesitation when coming out of what I presume is lean burn, it's similar to turbo lag in which the engine must be "awoken" after cruising to let it know we need some umph.

more driving (44 mpg on first full tank!) but the idle issue w/ the persistent cruise buck has got to go. The idle is almost different at each stoplight, sometimes surge/fall 1k-1.2k or 1.4-1.7k, etc, or it'll level out near 1.2 or 1.4k and be steady, never 600 like spec. I unhooked the TPS for kicks and drove it, every buck/stutter cleared up and the idle would be perfect if it wasn't for the 2k+ idle. Looks like I need a new TPS or just get another TB and be done with it.....Mak

You might want to double check the TPS wiring. Just make sure pin 1 grn/wht is connected to D22 sensor ground, pin 2 red/blu is connected to D11 sensor input and pin 3 yel/wht is connected to D19 reference voltage.

Didn't read through the whole thread. Did you sweep the throttle slowly and watch the tps voltage with a multimeter? I'm willing to bet that it's spiking.