saikou

This has been bugging me for quite some time, but not enough to dig into it any further. I do have some time off for Thanksgiving, so figured this time is as good as any to figure this out. 1993 Prelude w/ H23/5spd.

Every once in a while after I've started my car, the car will sputter and idle real low, almost to the point of stalling. When this happens, I try to give it some throttle, but the sputtering only increases. It wont completely die, but after a good 20-30 seconds of this, the idle will rise (not too high, about 1K RPM) and then drop down to normal idle speed - as if nothing happened. This never happens when the car is cold. Only after the car has been running at operating temperature or slightly warm and I attempt to start it up again. Also, I cannot pinpoint when exactly this happens - it could be after every 10 starts or 20, completely intermittent.

Last time it happened today, I had half a tank of gas and it had been sitting for about 1 and 1/2 hours after I parked at the gym. It's also happened when the tank was full and nearly empty. Doesn't matter. My car is stock for the most part - OEM intake, OEM header, OEM cat-back, catalytic converter. IACV screen has been cleaned out, EGR valve is clean, coolant level is normal, no CEL. I have a blocking plate installed in replace of the starting air valve also. Fuel filter, distributor cap/rotor fairly new as well as brand new NGK plugs as of yesterday. NGK plug wires are only a couple years old and the 02 sensor is about a year old. Checked the throttle cable & plate, all clean.

Any ideas guys? Thanks!

holmesnmanny

This can actually be due to a blockage of the egr ports. What could be happening is that the ecu tests the egr system when you start the car and when it does it expects to alter the timing. If the ports are clogged it could cause a weird start. I'm not sure on this, but this could be what is happening. I had this issue on my Camry as the Camry does the same thing. When I cleaned out my egr valve, which included ports on it, the issue went away. Your valve may be clean but the ports could be clogged.

saikou

Thanks for the reply. Luckily, I am familiar with the EGR port cleaning on these intake manifolds and you're right; they probably could use a cleaning. I just don't feel like taking that intake manifold off, haha! Might as well though with the holiday coming :'(

preludeNApower

I have had a blown headgasket to cause a similar scenario... Cyl 3 misfire at start up for about 30 sec. Compression test it

92PlayRude

I have the same problem with my 92, only at this point it happens every time that i have a warm start... I think I read somewhere a while back it could be caused by the MAP sensor being old/faulty/dirty, EGR ports would make sense tho..

saikou

Just a quick update:
Took the intake manifold off last night and to my surprise, all the bottom nuts were either loose or not tight enough - vacuume leak. Also, I just finished drilling the EGR port caps out and not surprisingly, with 200,000 miles, they were completely gunked up. Taking the manifold up to work to finish blowing all the crud out with the air compressor, since I don't have one here at home. Looking forward to putting this all back together and firing her up.

Also, all 4 of my fuel injectors have carbon build up on them. Is it alright to just have them sit in some parts cleaner over night without it doing any harm?

holmesnmanny

Just spray carb cleaner pointed down from the injector top side at that gunk and you should miss the pintle since there is a cusp around it. Should be fine. Just be careful as that plastic piece can break rather easily. I wouldn't try prying that gunk off much at all.

saikou

Exactly what I did as soon as I realized it was just soft carbon build up. On another note, I finished the EGR port cleaning and re-installation of the intake manifold with new gasket and injector o-rings. Does run a heck of a lot smoother and idles just as well. Did have 1 occasion where I was sitting in a parking lot after starting the car up and the idle dipped below 500 for a brief moment and I gave it some throttle. Cleared up after that. Will report back if I have any of the same symptoms.

saikou

Well, still sputters and backfires whenever I start the car up after it's warm/hot at idle - intermittent again. It's like it has to think for a minute how to idle correctly. Giving it throttle during this period, I hear a very noticeable backfire - almost seems like a lack of spark issue.

Also, having a problem getting my idle set. I'm doing it according to the Helms and the idle screw really has no affect until I screw it in all the way and it wants to die. Backing it out does not raise the idle at all - my FITV is blocked btw. Having to raise the idle by increasing the tension on the throttle cable, which I'm not a fan of because there is absolutely no slack in the cable now and the throttle plate doesn't exactly shut immediately as a result. With the intake pipe off, if you gently push your finger on the cable, you'll see the plate move.

Also, having a ticking noise coming from around the fuel injector area I think - had it before I did the EGR port cleaning as well. Prior to all of this, I did a valve adjustment last weekend and it had no affect on the ticking. Juuuuuuust about to give up, haha. Sprayed around some carb cleaner with the engine running for vacuume leaks and no dice. Any ideas?

92PlayRude

Ticking could be from injectors, try some injector cleaner ?

holmesnmanny

Did you ever compression test this motor ?

saikou

I have never done a compression test before, I am interested in doing so - would like to know if its boost ready, haha.

I have been running a bottle of Chevron fuel injector cleaner. Idle is still low, about 500-600 rpm. Also, I can hear it backfire out the exhaust slightly at idle, very audible but doesn't cause the idle to change. Let the car idle and took the butt end of a screw driver and started tapping the IACV and it did cause the idle to change - may have a problem with mine?

holmesnmanny

Just do a compression test first. Remember to remove the main relay to disable fuel and remove the ecu fuse to disable spark.

superCRXed

im having a similiar problem with my 88 crx and once i start the car it will run for 30 seconds or so and sounds like it drops a cylinder and studders like crazy. any suggestions on what it may be or what i could do to correct this problem. thanks

pissddrunx

IAT possibly or you need plug wires cap rotor.

Hondaguy83

Engine iac passages needs cleaning.
Supercrx,check fast idle. Take off cap and turn plastic ring till it shrug tight.

crazes

Have you actually checked to make sure that your radiator fluid is topped off. If so start your car let it warm up then take a number 10 and check to see if you have a steady stream of fluid. Pretty much your bleeding the system to make sure that there are no air pockets. Those pockets can cause a problem with idle surge

Hondaguy83

U said it sputters even when increasing gas then I would rule out idle air control.
1.ignition timing
2. O2 sensor giving false reading / lean/ rich because it runs good in open loop.
3.coil n igniter tends to give weak spark when car is hot.
4.clogged cat because when it heats up metal expands/ try hooking up vacuum gauge to manifold.
Comes down to process of emination. Good luck