88 CRX with D15z1 and DX trans - weird problems - Fuelly Forums

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Old 02-04-2009, 12:54 PM   #1
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Exclamation 88 CRX with D15z1 and DX trans - weird problems

I had Import Powerhouse in Phoenix install a D15Z1 engine into my 88 CRX and I have had some weird problems with it ever since.

1st, I thought I would be getting much better MPG than 42 avg, were my expectations off?

2nd, When I pump the brakes, my idle RPM surges from 500-1400, WTF?

3rd, If I go over 5K RPM I get and immediate check engine light and an CEL code of 16, until i turn off the car and restart it will not rev past 3K.

4th, the V tech seems to engage at 2700 RPM, how can i increases this to 3200 cheaply? Would it be cheaper to install a HF 5th gear instead?

5th, at cruise and maintaining RPM(1K-2.5K)/speed(any)the car surges making me adjust my throttle to compensate, again WTF?



I really appreciate any advice, help or even recommendations of competent mechanics.

I must say the guys at import powerhouse did a great job of installing the engine but i am thinking with these issues maybe they were out of there depth with the D15Z1 uniqueness's or maybe it something else entirely.
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Old 02-04-2009, 04:17 PM   #2
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With everything operating correctly, you should be getting better than 42 mpg average, especially in a warm place like Phoenix. Two caveats:
1) driving habits have as much to do with fuel economy as how the engine is running. I assume your 5,000 RPM revs are only for test purposes and not a regular part of your driving habits.
2) You may have improved the engine efficiency w/ the D15Z1, but you still have a relatively high rev DX transmission. Other members with a similar setup can tell you how their FE is. I think you can also search the garages as well.

The only info I can offer is for problem #3. Code 16 is fuel injectors. Beyond that, I have no clue what the problem may be.
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Old 02-05-2009, 03:39 PM   #3
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1 - I think that's very good considering your problems with the car.

2 - Sounds like the alternator maybe? Not sure.

3 - If you have a code, fix what's wrong before thinking anything else is to blame.

4 - Sounds normal.

5 - Could be normal too. If lean-burn is working, it does feel strange. With the non-VX gearing you might need to adjust the throttle.
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Old 02-07-2009, 06:35 AM   #4
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Quote:
Originally Posted by cems70 View Post
2) You may have improved the engine efficiency w/ the D15Z1, but you still have a relatively high rev DX transmission.
I started with an HF cable trans but the engine was burning too much fuel pushing those tall gears in 1st and 2nd, my FE went up 4 when i put the DX in
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Old 02-14-2009, 08:50 AM   #5
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Originally Posted by mcamodell View Post
I started with an HF cable trans but the engine was burning too much fuel pushing those tall gears in 1st and 2nd, my FE went up 4 when i put the DX in
That doesn't make a lot of sense. The D15Z1 engine's power curve is meant for the tall geared VX transmission. The HF tranny is only slightly taller than the VX tranny, so an HF tranny should have been good for 50+ mpg assuming the engine is running properly.
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Old 02-15-2009, 02:18 AM   #6
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suggestions?

Am ordering a new alt tomorrow, and i got new Fuel injector set in today.


any other suggestions?
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