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Hi everyone!
So I have an up until now faithful 1994 Accord EX 4-door Automatic with VTEC engine. All of a sudden about a month ago it started surging intermittently and it’s gotten worse. I thought it was an idle issue at first (CEL code 14 persists to this day) but now it’s doing it all the time even when the throttle is open. The RPM goes up and down, RRR – RARR — RRR — RARR — you get the idea. It’s bad enough that the engine moves back and forth like its nodding it’s head.
I’ve tried everything I found online as a remedy (thanks to Eric for the videos). Here is what I’ve done so far, some of which seemed to fix it but after a day or two it disappointed:
New spark plugs NGK iridium
New spark plug wires NGK
Royal Purple injector cleaner added to premium gas
Cleaned out original Idle Air Control Valve
Adjusted Fast Idle Thermo Valve
New distributor cap and rotor (did this twice, Duralast then YEC)
New air filter
New pcv valve (oem)
New antifreeze/coolant (oem) — bled system too, after every part change involving coolant lines
Replaced Idle Air Control Valve with New part
Replaced Fast Idle Thermo Valve with New part
New synthetic oil and filter
Disassembled throttle body and cleaned it out very very well including both sides and edges of butterfly and IACV passage, replaced TB gasket
New Throttle Position Sensor calibrated to .5-4.5 (original one tested fine too)
Tried removing vac line (plugged it) and wiring connector from EGR, no change in symptoms
Tried removing wiring connector from IACV, no change in symptoms at speeds above idle
Tried adjusting idle speed screw (paid a mechanic for diagnostic and that’s all he came up with unfortunately) which seemed like a fix but wasn’t.
Tried placing hand in front of open throttle body and engine stalled completely and quickly after hand was sucked up to the opening, my understanding is that pretty much eliminates a vacuum leak as the culprit?
Little to no suction on lower port in TB (FITV)
Lots of suction on upper port in TB (IACV)
Any troubleshooting ideas I can try?
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[quote=”ben_tech” post=157608]I’m happy to report that replacing the ECU / ECM module finally fixed the problem as far as I can tell. I mean I’m not 100% sure because it’s an intermittent issue and it’s only been one day but it’s very promising as it was acting up more consistently these days. So I tried dozens of ‘conventional wisdom’ fixes found on the Internet for the engine surging / idle issues but in the final analysis, “read the service manual” (the code 14 troubleshooting chart) was the solution when followed through all the way to the end.
I’ll never know if replacing all of the capacitors in the original ECM would have solved the problem. I replaced about half of them but didn’t have the other values. May or may not have been an avenue to pursue further for a low cost fix.
All of the other things I did (replacing all of the valves and sensors, full tune up and more) I’ll chalk up to preventative maintenance and a learning experience. All told it probably cost less than the dealership would have charged to replace just the ECM. That’s one way of looking at it.
Thanks again for the consulting, especially DaCoder.
Will update if the issue crops up again.[/quote]
Glad to hear it!
Your (you’re?) very welcome, the FSM is very helpful for finding stuff like this. I meant to say in one of my posts, that when something blows on a circuit board, usually you get a wave of failures behind it. The only REAL way to repair your ECU is to have a circuit diagram and full spec sheet, and test each and every component on the board.As far as the conventional solutions, I did that too when i was working on my 97 Neon, threw ignition parts at it until i realized that the wiring harness had fallen apart due to all the oil on it.
I’m sorry I’m barely getting back to this, but I’m glad you found the issue! So it’s fixed for good?
[quote=”hondaguy453″ post=159139]I’m sorry I’m barely getting back to this, but I’m glad you found the issue! So it’s fixed for good?[/quote]
Yes thankfully so. 🙂 Thanks again.
Sounds like a fix and I won’t argue with success. I’m still not a fan of aftermarket alarm systems. I’ve seen way too many problems with them to trust them. In fact, I spent a couple hours ripping the one out of my new Vigor. That said, I’m happy to hear you’re back on the road. Thanks for the updates and for using the ETCG forum.
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