1992 Civic VX FYI
 

I just joined this forum as I have been reading forums for quite some time but never give my input and would like to give back.

My current project/problem that I am working to resolve is an idle problem on a 1992 civic vx D15z1 (and yes I confirmed that the right head was on the right block). I got the car with the intention of making a great MPG car and have been working on getting everything back to stock specs. I am doing all work based on the Honda OEM manual for this car.

In attempt to get the car running smooth and idle down I put in all factory of the following. Wires, Plugs, distributor cap, rotor, timing belt, waterpump, ivac (idle control), thermostat, temp sensors. Unfortunately the idle is still around 800 and anything lower stalled the car.

I checked the following? Clutch petal switches, AC relay, idle adjustor (yes with the ivac unplugged then plugged back in and ECU reset. Timing?. Which I can never set properly as even with the jumper wire in the ECU plug it seems to self adjust. The previous directed me to check the cam timing which I did and even check 2 teeth each direction to see if that will help but nothing. I finally went back to the basics and checked the fuel pressure, even putting on a known good pump, plug gap and then the compression.

When I checked the compression I got 90psi across the board which is super low. Figuring there is an underlying problem I took of the head and brought it to the machine shop. For now I?m not going to do the pistons as the walls seem great oddly enough. I just picked up the head today and the machine shop said all the exhaust guides were shot and one of the exhaust valves was shot. I am waiting for a shipment from Honda for all new head bolts and gaskets which will be in on 3/8/11. I will update you on my progress. If anyone else has similar problems maybe we can swap ideas?

Re: 1992 Civic VX FYI
 

Also, I wanted to post as an introduction that I am mainly about making a car a fuel efficient as possible, but sometimes you require a bigger truck. I have decided to put the isuzu 3.9 4bd2t turbo diesel into a suburban. I bought a isuzu street sweeper and scrapped everything else and now the engine is sitting in my driveway. I still need to rebuild it and buy a suburban but the project is slowly coming along. The numbers that I have read are around 25-30 mpg from a suburban 1500.

Re: 1992 Civic VX FYI
 

Interesting idea. Is that an engine that was also found in consumer road vehicles, or only in equipment?

Re: 1992 Civic VX FYI
 

it is used in all isuzu npr foward cab trucks. There are tons on the road and the best part is that the pistons are sleeved so you can rebuild back to spec.

Re: 1992 Civic VX FYI
 

Very cool. Will you be using a manual or automatic transmission?

Re: 1992 Civic VX FYI
 

With an adapter kit from isuzudieselswapper.com i will get that and attach to a 700r4. you can also mount to a nv3500 manual with another kit

Re: 1992 Civic VX FYI
 

What is your idle problem? Idle too low? Idle to high? Surging idle? Doesn't idle at all?

Thanks.

, Bill

Re: 1992 Civic VX FYI
 

The idle is to high. And it surges slightly. The odd thing is that there are no check engine codes and there is even a slight surge when the ivac is unplugged (which you have to do to set the idle speed properly)

Re: 1992 Civic VX FYI
 

Do you have a helms manual? Try reading all the threads I've posted in regards to civic vx..
Here is a good start:
https://www.gassavers.org/showthread.php?t=12629
https://www.gassavers.org/showthread.php?t=12045

Everything discussed in those threads you should try. In case this isn't mentioned, make sure you re-do ALL electrical grounds. The helms manual will say EXACTLY where the electrical grounds are. Do you have a timing light? how many RPM is the car idling at?

Re: 1992 Civic VX FYI
 

Yes I actually have the Honda manual (I had the PDF printed and bound, it is a couple thousand pages in two books, but is great). I did not check if there are any missing grounds but will do that. And yes I have a very good timing light with a tach and volt reading on it. The idle does not seem to go below 850, and the timing does not want to seem to set. Even when I have the jumper wire on the ECU test connection, the timing mark seems to have a mind of its own and jumps around... weird Ive never dealt with that before. Thanks so much for any help. I will be putting the head on this week so will be able to play with it a but more.