I have a 92 accord lx that has been giving my endless hours of trouble. at 2 thousand rpm the engine chugs like its missing, but it only does this at exactly two thousand rpm. It also revs up when i put my foot on the clutch to shift. when it does this it stays at about three thousand rpm for several seconds before dropping rapidly back down to normal idle. I have just rebuilt the engine from the block up, changed the clutch, cleaned the E.G.R. port, put a new fast idle thermo valve on, new ignition system, new E.C.U., and much more. I’m at a loss at this point, no one i talk to has ever had this problem.
Why did you replace the ECU? Do you still have the old one?
+1 That seems like a shotgun repair. Do those things ever go bad?
Rebuilt? First test the compression.
Check valve lash. Clean the MAF sensor if it has one (My '85 and '88 Accords didn’t).
Clean the throttle body. Check the PCV system. Change the fuel filter. Check fuel pressure.
May be time for a re-manufactured distributor. Was that part of the “new ignition system”.
I assume there’s no check engine light on.
I should have been more clear. diagnostic work done by myself and two garages determined that the ecu was faulty, yes I still have the old one, changing it did nothing. Throttle body was cleaned both by me and the shop. They also checked and adjusted the valves, which was a waste since the head had mechanical failure and needed replaced. Compression test was preformed and determined that rings were needed. There is no check engine light. the distributor is brand new, as well as the coil, plugs, and wires. all sensors have been checked, cleaned, and reinstalled. New fuel filter, fuel pressure is fine. PCV valve is also new, and no vacuum leaks have been found. Upon completion of the rebuild, which I did myself, the engine starts fine runs great, but when I start to drive it produces the surging and chugging symptoms.Chugging only when i cruise at exactly 2000rpm, surging when I depress the clutch. When it surges it rises to and then holds steady at 3000rpm for a few seconds before plummeting back down to 700rpm which is normal idle. All attempts to troubleshoot the issue have failed to bring anything new to light.
Chugging at 2k makes me think one of the balance shafts was misaligned. It could also be due to the timing belt off a tooth or two, but that doesn’t seem likely. You sound like you’ve done rebuilds before. The balance shafts though, on a Honda, are tricky, especially the rear one.
Will it surge if you are idling in neutral, clutch out and depress the clutch or only between gears while driving?
I’m curious why the balance shaft would cause it to chug, could you explain?
I agree that the rear balance shaft can be tricky, but I followed all protocol in timing it during reassembly. So I feel that it should be right, “should” being the word used.
The surging only occurs if the vehicle has moved. Once stopped again it won’t reoccur until I Drive forward or backward. I can recreate the conditions on jack-stands with the wheels off. However the surging does not occur if I disconnect the vehicle speed sensor. One of the shops I took it to found this way to deal with it. Saying that a new ecu would fix it. That did not however turn out to be the case. I replaced the ecu at that point and there was no change. I replaced the VSS even, just to be sure.
Were compression and valve lash checked AFTER the rebuild?
I have not rechecked compression yet, but valve lash yes.
I was thinking that if the balance shafts were off enough that the vibration might be so bad that it feels like chugging.
This chugging, does it do that in neutral or only when driving? Can you get past 2000 rpm while driving and does the chugging go away when you do? The jump in rpm when you push in the clutch, the has to be moving? It won’t do that at a stop? It will do it while slowing down to a stop and you push in the clutch to keep the engine from dying?
Balance shaft Out-Phase wont do this…
Accords suffer from Distributor woes a lot…also cap and wires can do this…(even new and supposedly fine bec they’re new) I had an issue on my Prelude that I SWORE couldn’t be the wires…drove me nutty till I broke down and swapped in some new ones…Purred like a kitten thru ALL RPM’s till I sold it 8 years later… SO I would try to find a known good Distrib…and swap it…also swap some wires…
ALSO…make CERTAIN to BLEED YOUR COOLING SYSTEM…You are aware of that bleed nipple near the thermostat housing no? Failure to do so will mess with ALL SORTS of things that the ECU is monitoring…temp…mix adjust/based on temp…high idle/low idle…etc…super important
The chugging occurs only if the vehicle is in motion, never in neutral. I can accelerate past 2K and it stops, it does it in all gears. If i let the rpms fall back down to 2K it will chug until the rpms fall below 2K. It seams like once it starts, the rpms tend to hang at 2K as it chugs (or lunges), until i brake or give it gas.
For the surge in rpms to occur the car has to be moving, forward or reverse. The clutch must first get depressed, and then even if I put it in neutral, the rpms jump and hang at 3k. This symptom occurs during both acceleration and braking.
The coolant was bled during reassembly. Also this is the second set of wires I’ve tried on the car, the first were used, and these are new. The wires that had been on when this problem all started had about 3K miles on them. These issues all began at the beginning of last year, so I have had a lot of time to try different things. Luckily i have my Integra to keep me on the road.
A friend has recently suggested that the chugging could be the TPS, if it had developed a “flat spot” in the rheostat wire itself at approximately 2k rpm. He thinks that this would not show up on a voltmeter. Does this sound possible to anyone?
If it were the TPS, a flat spot would show up on an Ohmmeter. It should also show up on a voltmeter, but not necessarily so. If the power supply were a regulated power supply, the voltage would remain constant through out its range but the current would vary. More than likely the voltage would vary smoothly through out its range.
The typical TPS has 3 wires - a 4.5V reference voltage is sent to it over one wire, another is the ground, the third is the signal return to the PCM. If you power on the car (normally would not need to be running), and backprobe the signal wire, a typical TPS set up would be to have about .5V at closed throttle. As you slowly open it the voltage should increase smoothly and steadily up to something close to 4.5V at WOT.
Its a simple thing to do. Those specs are typical. I’m sure you can find something online to verify for this car.
The only problem with the TPS theory is that it would be less RPM dependent and more throttle position dependent. The surging would occur at different RPMs if you were going uphill as opposed to down hill. You don’t have V-tec so that system would be ruled out. Do you have a set of butterflies in the intake manifold to direct air into a larger intake port at higher RPMs? I don’t recall Honda using this technology, but they might have tried it. If it does, then I’d think that they were opening too soon.