1995 accord idle surge.
 

Ok so first off, my 97 accord got stolen right after I did another head gasket on it and replaced the smaller timing belt. Awesome times.

Replaced it with a 95 accord I picked up for 300 bux. Bought it with a known issue of idle surge. According to previous owner it's had new head gasket (I can see the tab of what appears to be new hg) head machined, new timing belt, and new IAC.

Car came with a new throttle position sensor since it still had the surge issue. I've installed that, tightened the fitv, and bled the cooling system, surge persists.

Since it doesn't have odb2 my code reader is useless, but we did jump the connector and it gave us code 4, crank position sensor. I got no problem with replacing that, but I doubt that is the cause of the surging idle.

So whats left? I've visually looked and listened for vacuum leaks haven't found any. When it is surging I can hear what sounds like a flap getting slammed opened or closed in the airbox or air tube somewhere. (not sure if thats relevant) I've seen posts indicating that it could be a map sensor, but thought I'd seek advice here before I just go changing another part.

I gotta get this car up and going for the ol lady cause we're sharing my truck right now, and we really need the fuel mileage of the honduh, and I gotta get her the hell outta my truck.

Thanks in advance!

Does the idle surge at idle? You can pull of the snorkel from the throttle body and use your finger to cover the lower port that goes to the FITV. If the idle stabilizes, then your FITV is likely the issue.

A code 4 can be from the crank sensor, the wiring, or possible the ECU. The crank position sensor is inside the distributor on the 95 accord, so check the wiring inside the distributor and the electrical connector before replacing it.

I'm with PA - rarely do the TPS or MAP sensors fail on these even though many seem to replace them all the time :shrug:

Be sure the coolant is properly bleed of air, clean the FITV and the IACV....be sure the coolant hoses to them are clean and allowing coolant to flow. Then since there is strong evidence work has been done to the head, you really need to check for any vac leaks....doing a HG replacement many will get the intake gasket wrong or the injector seals...then there are other sources...other gaskets, vac lines, ect.

Rock on! Thanks guys! I'll see if I can get a mini torch over here and try to hunt down a vacuum leak.

We've had the throttle body on and off about 4 times now, the kids are getting good at it. I'll check the distributor wiring for the crank sensor and worst case replace the sensor if I can't find any bad wiring.

Also, if I physically close the throttle linkage, (close it further than the spring does) it stops surging. I'm not sure how to factor that one in...

Finally got to get back on it today... Er, well got a new battery in it so we can start it on demand... We've been waiting on title work and all to get it tagged before I put any more work into it...

Still surges, but today I noticed that it seems like there is alot (ALOT) of exhaust pressure... I'm talking you can stand 4' off the back of the car and it's blasting your pants.

Surge is between 1k-1250 and it does it in gear, once you get going it's ok, but say you go to try to hold a steady pace, and the surge is back... (I think, feels that way on surface streets, not hi-way tested yet)

Still throwing the crank position sensor code, out of money for now so we'll be getting that (or checking the wires this weekend) next payday. Hope to get my brother over tomorrow to help check for vac leaks... Ugh. I don't wanna tear this thing down...

Question: With the previous owner having had the head gasket re-done and the timing belt... Is it possible, that they got the timing slightly off (like a 1 tick)?

The only other thing I can think of is I've seen some having the same issues with a intake manifold gasket issue...

Thoughts?

Ninja edit: compression is 180 on cyls 1-3 and 190-ish on cyl 4

You can always check the mechanical timing. You'd have remove the valve cover, get the crank to TDC, then see if the cam sprockets are at TDC.

Did you ever try this suggestion from my earlier post?

Crap. I think I did but I don't remember the result... I'll re-do and report back.

I do know I did remove the the fiv and tightened it back up with no change. And it surges regardless the temp.

Put new battery in yesterday and it seems it's harder to start and running a bit rougher...

won't really idle, just surges. I'll try to get video... It used to be I could force the butterfly closed and it would settle, but it won't do even that now.

Well, 1 tooth off will let the engine idle and idle smooth (if it actually starts), but it won't really let you rev the engine (it struggles). So if yours will free rev, then it's not a tooth off. I just went thru that in October on my 99 Accord that I had just bought. On it, the harmonic balancer had come loose, and the key walked out of the lower pulley about 1 tooth. It would run, but it was a dog. Fixed it, and it runs sweet.

Usually a vacuum leak is pretty steady and wouldn't raise and fall. To me that sounds more like an IAC (Idle Air Control) valve. I'm not sure if your engine has 1 or not though (it might be combined with the FITV).
Another thought would be that you've plugged the IAC plug into the TPS, and vise versa. I think I've read that somewhere in this forum that it can happen, and you have had the head and intake off. Maybe??

Went out today and tried that. No change. See videos... er, well I didn't video doing that test, but they show how it behaves.

See I have almost the exact opposite issue. engine will rev just fine, but will not hold idle or steady throttle input.

I can put closing pressure on the butterfly and the idle settles down and idles normal. I'm going to be checking the adjustment on the new tps and make sure it's correct, but I don't see that causing this issue as it was behaving the same before the tps was installed. I'm also starting to suspect the IAC, but a new one was put on before I bought the car, I suppose it could be a bad one but, I dunno.

anyhow here's the vids...
https://youtu.be/ABMZHSZwUUQ

https://youtu.be/ieM-o4pFoO0