Hi, I have (for 14 yrs.) a 1995 Toyota Corolla 1.8L, 5 spd. automatic, OBD1, 385K mi. It’s driving me crazy. I’ve been driving for a year wear this what you’d call “hesitation.” (I am somewhat of a mech.). The car starts fine and idles perfectly. So smooth you can’t even feel it. When any gas is applied it sputters and chokes. Only gets up to 25 mph after a mile or so. Ppl are beeping horns and angry at me. It’s dangerous. I’ve done everything (almost)(see below). So I believe that the car ECM is in “fail-safe” mode (aka, “limp mode”)(I have the orignal '95 Corolla Manual). That could be any one of the input signals to the ECM, or the ECM itself. I doubt it’s the ECM or the wiring. I’ve changed: 1) the VSSensor 2) the MAP sensor 3) the TPSensor 4) the Fuel pump 5) the fuel filter 6) the fuel injection rail Fuel Press. Regulator (operated by vacuum) 7) The plug wires and plugs 8) the Distributor (new) 9) the AIT sensor 10) the Battery 11) the motor mounts 12) the Tranny gear change solonoids, all three. I have checked for trouble codes many times over the past year. At first there were trouble codes like 6-1, 6-2, 6-3, transmission. That’s why I changed the three solonoids. There were a few other codes (in diagnostic mode check), but they have disappeared. It may be there false touble codes which would indicate ECM. My understanding is the ECM rarely goes bad on this car (Canada made). I don’t have much money. I’m just now begging friends for me to buy an ECM. (rebuilt. there are none new anymore).
Question: I hear that is a common problem (the hestation, jerking). What is the common cause? Thanks, All.
With 385k miles, nothing is common. The engine is weak and hesitates? No big surprise with this many miles. Have you run a compression test lately? Ever?
Run one, I think you’ll find your problem.
Thx, Mustangman. Although I hadn’t thought of that (compression), I highly doubt it. Why? B/c just since summer 2018 it was running fine, full power, no problems. The prob. suddenly came up one day. I think it’s not compression, rings, etc. It is electronic or sensor or ECM related. The car has been babied by me since I bought it with 60K miles in 2006. Any other ideas, man?
Yours,
george
When was the timing belt last changed?
If you haven’t checked compression, you don’t know it is not a problem. You are only guessing.
You guessed in the past, changed a bunch of parts, spent a lot of money, did not solve the problem. See where I am going with this?
Yeah, Mustangman. Thx for your attention to my car problem. Well, then I’d have to buy a compression gauge.
So, I would certainly expect that a compression loss would happen gradually, over time. And not suddenly like the problem did (I had to get towed home off I-95). That’s why I think a compression prob. is not the problem. Also, I think that would show up at idle, also. Idle is smooth. Car starts every time. I don’t think it’s compression. But maybe I could borrow a tool from someone.
Also, in case you weren’t aware, this model and year car ('95) is well-known as one of the best engines ever made (Canada),.
But, in a sense, you’re right about the just doing the comp. check.
Thx much,
George
Probably not a real major problem but it is not a good idea to put your email address on an open web site.
Have you performed a back pressure test . . . ?!
rent one for free at AutoZone or AdvanceAuto
Poor compression is certainly a possibility, but unless accompanied by a rough idle/difficult starting, I doubt that’s the explanation. Especially since you say the engine starts easily and idles smoothly. A defective PCM is an even less likely explanation, so don’t waste your money.
A much more likely explanation would be a defective fuel pump/clogged fuel filter, plugged air filter, or plugged catalytic converter/exhaust.
Well, friend, I did all those things. The fuel pump screen (in gas tank) is/was clean as a whistle. I even replaced the fuel pump (Upick salvage - but it was also good, clean). I replaced the fuel filter a year ago (new). No change. I disconnected (recently) the exhaust pipe (before the converter) from the manifold. So it was then an open system with no back pressure. No change.
I agree, I think it’s unlikely the ECM (you wrote PCM, a typo?). But b/c I was getting trouble codes months ago, and they have all vanished, I presume that the ECM was giving false codes. That would point to ECM, no?
George
I bought a used fuel pump from the “you pull it” junkyard for my Daewoo Lanos. Sure, it “worked” but the fuel pressure (as tested with a pressure gauge) was about 5-8 PSI below spec. And the fuel gauge wasn’t accurate, either.
I ended up buying a new fuel pump on Rock Auto, and using that one, which gives the desired pressure. Based on this experience, I will NEVER buy a part like this from a junkyard ever again, even if the car appears to be low mileage and good overall condition. I wasted $30 on the junkyard part, when new cost less than $100 delivered to my door.
powertrain control module
not a typo . . .
I couldn’t agree more with @bcohen2010 in regards to buying a used fuel pump from a junk yard
I wouldn’t hesitate to buy a used door panel, fender or many other things from a junk yard. But not a fuel pump
I would connect a OBD2 reader and try checking long-term and short-term fuel trims, paying attention how short-term fuel trim changes between idle and high rpm, it might pinpoint insufficient fuel delivery on higher RPMs
I’ve read before about rare condition when fuel rail damper was giving some similar symptoms, cheap to replace, not sure how to test
just throwing some ideas into the pot
op can’t do that
oh, I missed that, in the first line…
Check for stored diagnostic codes again. Especially if you’ve disconnected the battery while debugging. It takes time for the codes to re-appear.
I have a similar vintage Corolla. Never experienced that exact problem. However I did have a problem with the engine not responding properly to the throttle. Instead of a smooth transition it wouldn’t do anything at first press, then would jerk forward. This was caused by clogged fuel injectors. But in my case there was no problem with the engine sputtering or choking.
The throttle position switch should be check for this symptom.
EGR, PCV faults could cause this too. As well as anything causing a lean condition, such as a vacuum leak. Likewise a suspect is a clogged exhaust system. For the vacuum leak you’d usually get a too-lean code, but not always. A fuel pressure check makes sense too, particularly if you can do a live version where you watch the fuel pressure as you drive.
If you want my wild-guess, EGR system problem.
A timing belt that has jumped one tooth could do that.
If you have a timing light, I’d also check ignition timing.
Could be a corroded electrical connection in lines to the fuel pump, coils etc.
I’d do some probing with a voltmeter and maybe a scope.
db4690, sir,
Re: Powertrain Control Module, Thx for the correction. This is an OBD1 vehicle. I don’t know if there’s a PCM. I think it’s incorporated in the ECM. I have the original '95 Corolla Shop Manual. I’ve been though a lot of it. I don’t recall a seperate PCM.
Also, yes, I agree that you never know what you get in a junk yard. Esp. with a 24 yr old car. That was the first thing I thought of, fuel pump. But this is Toyota Corolla and I believe the U-pick fuel pump was an OEM. So, I don’t think it was bad. I can’t readily check the fuel pressure b/c there are no nipples and it takes a special tool to tap into the fuel inj. rack fittings.
Also, sir, I was cautioned about using my email on this “open” forum. I don’t know how to exchange e-mails on this medium with the “code names.” Can you assist in that knowledge?