Ok I have a jdm d15 in my 90 crx which we converted to obd1 and mpfi when swapping in the new motor that being said lets move on. I have been having idle issues for the last 6 weeks originally it was constant at first then I set the idle by the book and at times my idle will drop low and run like crap. I have chk'd for vac leaks and what not, the car will cold idle fine and also warm idle fine until after you drive for awhile then you get the surging when at stops. I took off the manifold (skunk2) and found the brake booster fitting was loose so I fixed it with some epoxy redid the coolant and bled it put a new gasket on for the TB (edelbrock) just to be safe. I have also swapped tps sensors and set by the book 45 closed and its @ 4.5-5.0 when @ WOT. My a/c was also not working so I had my system recharged last friday before doing all of this with the gaskets and manifold and such over the weekend. Needless to say that I drove 50 miles to work and had no idle issues till I turned on the a/c and my idle went upto 1500rpms then slowly dropped to about 1200rpm then down to over 1k then started to bounce back and forth from about 1100rpms to 1500rpms at 1 point it settled then right back to surging. I let it go for a few minutes bouncing away then turned the a/c off and the idle dropped back to normal, turned the a/c on and bouncing again, a/c off idle drops back to about normal again.

So Im at the point of being totally clueless - I have no cels at all the car runs just fine other than this and the damn idle issue sometimes when at idle if the fans kick on the idle will surge also. This is all stock beside I/H/E and skunk mani and edelbrock TB. The motor is a solid 220 across the board on compression running a stock p08 ecu.

I will say that I swapped out the iacv for a used 1 but that 1 gave me a code 14 so I went back to the original which is not throwing a code (not that that means alot).

i mean cmon its a honda and god knows we have all had our share of idle issues but usually I get mine worked out in a day or so and move on but this one is frickin killin me .

Basically I have searched idle issues for the last few weeks and read tons of info but none of which seemed to help, I guess I could dump some cash for a brand new iacv and hope for the best but would really like info from people who have beed where I am at this point or people who can maybe give me some new ideas.

 

Well I decided to swap out the p08 for a p28 for the hell of it to eliminate ecu issues and then drove with the p28 to work this morning. Every light I came to and stopped the idle settled normally sometimes a little low though then I ran the a/c came to a stop and idled about 900rpm or so. But I am not sure only after a 45 mile drive that the problem is gone yet, I mean it would be nice to finally have this be so simple. I could just get the p28 chipped with p08 maps and maybe be able to move on. I will report back after driving home tonight.


Still looking for input though

 

ac switch. maybe thats sending wacky signals to the computer i dont know how those old ones work.

 

I had the same problem. Do your lights serge and then go dim? if so it's the regulator on your alternator. You will need to replace the alternator.

 

Check the TPS sensor... on an OBD2 car it should read 10% when the throttle is full closed. With a OBD1 car you will need to back probe it and check that it reads 0.5V when closed...easiest to backprobe at the ECU.

 

well its been a week or so and it seems that the p08 was the issue and the p28 seems to be working just fine. I guess Ill get the p28 chipped with p08 maps and i already wired up the 4 wire 02 its just running rich somewhat with the p28.