psiguy

So, bear with me here, this is a long one, and a mechanical f*cking mystery. I have a problem with my 90 Honda Accord. Again. But this problem is a bit different than anything that I've been able to find ANYWHERE on the internet.
A mechanic friend and I passed ideas back and forth to try to figure out what could possibly be causing my problem. Let me back up a little...

THE PROBLEM

My car runs great. It's awesome. Starts right up, runs perfect.
Until it gets warmed up. No, I can't even say that with confidence anymore.
It messes up when it feels like it, but never within the first 5 minutes of driving.

The problem it has, I'm assuming when it gets warmed up, is that is loses power.
The specific symptoms go kinda like this: Driving for 5 minutes, everything is fine, car gets 0-60 in 10 seconds or less, suddenly some ******* pulls out in front of you. You have to slow down. You go to get around him, pressing the pedal down about halfway. The car starts studdering and backfiring slightly at first, then more and more the longer you hold the gas. You let go of the gas and the car goes back to normal rpms. Press the gas, car studders again.
Press it in more, car starts backfiring. Press it in all the way, the rpms go down to about idle speed. Let go of the gas, everything is fine, back up to normal again. This happens every time you press the gas more than a quarter inch in. Less than that? You're either keeping your speed or losing it very slowly.
To me, it seems to be flooding the engine. It smells strongly of gas if you floor it until the rpms drop.

That's one scenario. Another is coming from a stop. You stop, look both ways, and you press the gas. Only to find out that the car starts shaking and backfiring after you reach about 3 mph. Keep pressing it in and your rpms drop and your engine slows way the hell down to almost nothing. It won't stall though, which to me, implies you aren't getting any gas at that point, otherwise it wouldn't be able to light the gas and it would stop. Say you lightly press the pedal in, you start to go. Slowly at first, then eventually you're gaining a whopping 5 mph every 30 seconds.

This is my problem. More details ahead.

A temporary solution is to cut the engine and let it sit for a good 30 minutes or so. It seems to work after that.

Note: the engine never overheats or even gets above a quarter of the way there.

Now here's the fun part. Where you guys make suggestions and I shoot them all down because I've already replaced those parts with brand new ones.

Continued in new post.

If somebody with better summarizing skills than me can make this shorter to read, please do. I just want suggestions and hopefully an answer.

psiguy

The things I've replaced on this car to try to fix this problem.

This will be a (hopefully) simple list with brief reasons as to why items were replaced if not obvious.

Keep in mind this is a 1990 Honda Accord LX.

1 Fuel pump. I thought it might have been a gas delivery problem early on.

Just short of a pound of rust from gas tank. I didn't add this, obviously.

1 factory original fuel filter. The previous owner was clearly retarded. Full of rust.

1 Entire Distributor. We thought it may have been a sparking issue. We weren't wrong to change this, as it was pretty burnt looking inside.

4 Spark Plugs and Wires. The tips were actually crimson red with rust.

1 Thermostat. I lied, this was one of the first things we changed due to the possible overheating element of this mystery.

1 Coolant Temp Sensor It was the next cheap thing on our list after thermostat.

1 ECU After we saw the burnt out resistors on the TCU, we decided that we'd throw in a new ECU we had laying around because it may be a computer problem.

1 EGR valve. After much googling, I discovered how much emissions bullshit sucks. And I had a hole in the side of my old valve.

Removed and cleaned entire throttle body and intake manifold It was on my way to cleaning out the EGR ports and valve.

Made EGR ports spotlessly clean More emissions bullshit. Seemed most likely culprit at the time. I was very disappointed to find out my only newest lead was a dead end.

4 Fuel injectors The car ran fine with the old ones, but after the 24 years of rust and dirt built up in the fuel filter, I had to be sure.

1 TPS Thought it might be this before we thought ECU.

Please, if I missed any potential causes, let me know. I think I have it pretty well covered.

Somebody recently mentioned oil leaking into my cylinders via a cracked head gasket... There's no oil in my antifreeze. Replacing a head gasket is my next step though if nobody else comes through for me. I've got a timing belt and water pump ready to go on too, just didn't want to put it on until I get the problem fixed. Don't want to have to pull my motor apart more than I have to.

mr500cm

I had a maxima that did just about what you were saying.....check into the fuel pressure regulator.

Lost Again

A lazy O2?

EDIT: I'm assuming there are no stored codes in the ECU. Also after checking for codes, go ahead and unplug the O2. Drive the car, yes the CEL should come on (that is ok), does the issue go away or at least get better? Just me but the fuel pressure regulator would show all the time - sounds more like an issue when the car goes into "closed loop".

psiguy

I forgot to add;
There is only one check engine light code on.
This car ran like it does now even before it was on. Code 12. But it only comes on once the car gets put in drive and goes about 20 feet. Hot or cold engine, it doesn't matter. Turn off the car, code goes away until it starts moving again.

I believe 12 is an EGR system code, which would still explain the problem, but not since the car runs amazing until it doesn't. That, and since the code wasn't on before I changed the EGR valve and cleaned the ports.
And those ports were full. Couldn't get any air or cleaner through them at first. And the valve had a hole in it. And THAT didn't throw a code. I assume it's because of the high flow exhaust with no catalytic converter and such.

Also.

1 TPS I Did, in fact, change the tps. It was the 3rd or so thing I tried.

The o2 sensor is in currently, but before when I had just replaced the exhaust I had it plugged. The exhaust came with o2 sensor bolt on covers.

It didn't help after it got going, though it did throw the code for it the whole time.
I might grab a new one anyway, it's right at the top of the manifold and not that expensive.

And as for the FPR, I replaced that at first also. But when it didn't help, I ended up giving to a friend who needed one. But I threw a new o-ring on mine and cleaned it out anyway.

Any more thoughts?
I wish I had a camera to show you guys exactly what the car does, but mine has been lost for a while.

I'm thinking about throwing a thousand dollar price tag on it and putting it up at the local autozone. It'll run great for a test drive, lol. As long as it's only about 5 minutes.

accordturb96

from what I read on pro demand, another tech had a similar issue with the egr code. Its code 12 egr system fault. What he found was the egr system and passage were great but the issue was found to be an open wire in the egr valve harness. Sound intermittent or based on load.

accordturb96

have you checked your timing? The belt could be stretching, the gear could have a sheared off or broken key on it. Just a thought. Sounds like it's changing.

psiguy

Timing belt was one of the next things to change, but I wasn't going to do it yet until I fixed the problem. If it turns out to be the problem, I'd feel pretty stupid. Wouldn't the timing belt stretching make it run like crap all the time? Same with a broken tooth. It runs perfect, no misfire or anything until it starts acting up. The car runs better than any of my others when it's first started. Up until the point that it starts messing up.

As far as the EGR valve harness throwing a code, it might be. I'll try throwing my old one back on with tape over the hole and see if it's the problem. Maybe from taking it off so many times.

accordturb96

well if the belt is stretching or doing weird things as I have heard, its only and issue when you command more fuel and motor, so upon the demand the engine turns harder which may be stretching it a bit. Just an idea Im not for sure on it though.

Lost Again

So you leave out the "known code" and ask for help mystery - solve the code and I'd bet you solve the "mystery". Again this is a "closed loop" issue.

Why do you leave out the fact that you have a code showing up, yet ask for help?

Again, introduce another code (43) by un-plugging the O2 and report back as to how the car acts.

For an egr issue - yes you cleaned the valve and the ports but did you ever tested the solenoid.....well again time to solve the code being given before going of the beaten path - you have a code, you have an issue driving the car and don't want to "solve the code"?

Sorry if this comes "off" as me being an A Hole but you did leave out some pretty important info.

psiguy

The code is within the last 2 days. I've had a problem with the car for the last year. Yes, I want to fix the code, but it seems pretty unrelated to the problem I have, especially since the problem long predates the code.
Also, some more information that I thought was pretty irrelevant, the old EGR valve that had a hole in it, when I pulled it off the previous owner had apparently put a piece of metal under the gasket to stop it from even being used. It was plugged in, vacuum line connected, and bolted on, but there was a piece of metal blocking up both holes that go into the EGR ports from the valve area. I removed this metal when I cleaned it all out and got a new EGR valve.

Again, the car still acts the same way, with or without the o2 sensor.

accordturb96

the egr system is detrimental to the car running as it introduces gases back into the engine. It can cause running issues. 02 sensor would be even more detrimental but the two work in conjunction with the motor. ignoring at hand issues is everyones point right now. Fix what you know is broken and move from there.

tech8

The OBD system on these early Hondas is kind of rudimentary, it is possible there was an issue with the EGR system causing the drivability problems that did not throw a code previously.

The EGR system may merit looking into as the source of your problems, instead of disregarding as a possible cause.

As shown in the service manual, an issue with the EGR control system can cause:

- Irregular idling
- Frequent stalling after warming up
- Poor performance, misfire or rough running

psiguy

It can't hurt to fix it.
Alright, so lets say that this problem finally decided to throw a code.
Maybe when I cleaned it all up and replaced the EGR valve it finally noticed that the problem it was having was caused by the EGR system. It's not unheard of. Maybe I unstuck a valve.
The code DID start in the last few days. Right after I drilled out the EGR ports and cleaned them.

With all that in mind, what could be throwing this code?
EGR Valve, Brand new and plugged in.
EGR ports, almost spotlessly clean.
Vacuum line, connected.

The valve moves freely by hand with a little effort.

Also, maybe of use: after near complete overhaul of EGR system, the car ran for about 200 miles in a single trip (newspaper delivery). The car only started acting up around mile 175 with the engine light on the whole way.
That's the longest it's ever gone with no problems.

accordturb96

check wiring. might be above your ability unless you're good with a multi meter. Need to make sure its not shorting

brakedrum

The way your 90 is acting is so identical to the way my 93 was acting with the bad o2 sensor, and the rich/lean fuel mix it was causing, that I'm sorry to hear it's not the o2 sensor.

hondamark35

just from the drivability issues you're describing this sounds extremely similar to an issue I came across on my sister's 2nd gen integra. the car would run alright until it warmed up then I would drive like crap, the more throttle you gave the more it bogged.

what finally fixed it, or what we discovered was that the matrix material in the catalytic converter had begun to break down and melt, clogging the exhaust flow. we had maybe 10% flow through the cat! we put a test pipe on and all of the issues were gone. ordered a new cat and didn't have any more trouble.

holmesnmanny

Idle the car and let it warm up completely. Disconnect the egr valve connector. Drive the car. When the check engine light comes on see if the issue gows away. If it does, the issue is egr related. Report back for further instructions. If it doesnt go away, leave the egr valve disconnected and now disconnect the oxygen sensor connector. See if it still acts up. If it still acts up, remove the oxygen sensor completely from the exhaust manifold to test if your cat is clogged. Test drive and see if the car runs fine.

DCFIVER

Sounds like a bad O2.....

psiguy

I'll find out if the problem is with my o2 sensor tomorrow by changing it out when I do the brakes in my other car. I'll take it for a test run for a while and if it still acts up I'll unplug the EGR valve.

As for my cat, I don't really have that problem, as this is my exhaust, and it's brand new. Like, just put on last week. My flex pipe was broken, and the previous owner cut out the cat for 75 dollars in scrap. :/

I doubt it's collapsed or anything. But I can take it off with 6 bolts, so I might as well check it anyway. I wanna see how nasty it looks anyway. See if there's more soot than normal, since the engine seems to flood when it's acting up and I press the gas.

Lost Again

Yea that is what I thought until the OP stated that there is known EGR code as well.

Since the car is OBD-I, it could be two issues - known egr and a lazy O2. Follow the code(s) first.

holmesnmanny

It may not just be the oxygen sensor it may be an exhaust leak before the oxygen sensor causing the car to run rich.

If it was isolated to the oxygen sensor I would first check for an exhaust leak before replacing it on a whim but it's entirely up to you.

It takes about five seconds to remove the connector.

lude-de

My 91 Prelude had the exact same symptoms a few years ago. It was sporadic, and a real pain in the *** trying to start out with a 5 speed.

My Prelude had the B21A1 ODB1 with fuel injection. If you're carb, this won't apply, but if you've got PGM-FI then the systems are similar.

In my case, it ended up be the Electronic Air Control Valve (EACV).

psiguy

About to go work on the car now.
Also, my air control valve was nasty when I cleaned up the intake manifold and throttle body. It was so full of carbon that it took me an hour to get it all out, but I did get it all. I've got another one on another motor, I'll see what replacing it does too.

psiguy

None of the posted solutions have helped. The o2 sensor was bad, I replaced it, no effect. At this point, it seems I need to jack up the radiator cap and replace everything under it. I don't have the time or money for that, and this car has been trouble from the start. Putting it up at the local autozone parking lot with a price tag of 1200. People around here buy cars to ship to family in Mexico, so I likely won't see this car ever again, and it should be gone by tomorrow.