1998 Check Engine Flashing - Toyota Corolla, Chevy Prizm (1998-2008)

I have a 1998 Corolla with 150,000 miles on it that started with an intermittent check engine light this summer. All four injectors were replaced at that time. It seemed to run pretty well for a couple of months then started running very rough, missing on the way to the airport. Put a can or three of injector cleaner through it and it ran better but the check engine light is on constantly now. Codes are random misfire. One local garage couldn’t find anything just suggested a tune up. Put new plugs and wires on, may have helped a little. The coils check out ok on their resistance at least. Seems to be worse when the engine is cold and on acceleration. Conflicting reports as to the compression, Toyota when they put the injectors in, suggested the compression might be off some, but the local garage said the compression was fine.

Thanks

Did they check and see if the misfire was on one cylinder or jumped from cylinder to cylinder. The fact that the problems keeps coming back means that they might have changed parts that might have still been good (hope that you kept all the old parts).

If the misfire was on one cylinder - I'd check that one for compression compared to the other ones. Might be a burned valve causing misfires.

If it jumped around - could be a fuel pump issue. Fuel filter is inside the gas tank - usually lasts the life of the car, but might be worth checking out. Pump might also be going bad, a couple of bad tanks of gas or running the tank at low levels will shorten its life considerably.

Other cause might be a blocked or leaky exhaust system, leaky intake system, bad O2 sensors, clogged cat, bad ECM, bad sensors (crank sensor), or lean fuel conditions (hole in gas line).

Did they check and see if the misfire was on one cylinder or jumped from cylinder to cylinder. The fact that the problems keeps coming back means that they might have changed parts that might have still been good (hope that you kept all the old parts).
If the misfire was on one cylinder - I'd check that one for compression compared to the other ones. Might be a burned valve causing misfires.
If it jumped around - could be a fuel pump issue. Fuel filter is inside the gas tank - usually lasts the life of the car, but might be worth checking out. Pump might also be going bad, a couple of bad tanks of gas or running the tank at low levels will shorten its life considerably.
Other cause might be a blocked or leaky exhaust system, leaky intake system, bad O2 sensors, clogged cat, bad ECM, bad sensors (crank sensor), or lean fuel conditions (hole in gas line).

Thanks much for the prompt reply, the misfire did jump from cylinder to cylinder, I have thought about the fuel filter and pump. Is it possible to replace filter without replacing the whole pump?

You can replace the filter without replacing the pump - but you will have to pull the pump assemble to get at the filter. There is a large "sock" filter that filters out larger particles and an inner fuel filter that filters the fuel before it runs into the fuel pressure regulator. Everything is under the rear seat cushion - access panel is on the driver's side of the car.

Bikeman982

Any update? Has your car been fixed and if so, what was the corrective action? I have replaced the fuel pump and filter included with the assembly for my 1994 because the fuel gauge was stuck and not reading anything but halfway. Now it is working great and if the filter that was attached to it is causing your car to missfire, I would like to know if that was truely the cause, or if it was something else.

theres a fuel filter in the engine bay below the charcoal canister on the 93-97. i had mine replaced after there was an issue with a powder like substance in my gas tank that may have killed the fuel pump (114K miles, may have just been its time). the prefilter was covered totally in a white powder and after seeing that i had the fuel filter changed out too. i opted to have a shop do it because i couldnt get the fittings loose and was afraid i would bend a steel line too sharply and break it.

Thanks for the inquiry Sorry to say it is still not fixed, a different local mechanic felt that it was a bad coil. I got a new coil and replaced one of the 2 coils. Replaced the coil supplying the no 1 and 4 cylinder as the P0304 code caomes up more frequently than any other cylinder the P0300 is still the most common code by far. The fuel pump will probably be the next thing I replace, but if the fuel pump is bad would it still run good once it gets warmed up? I can reliably get the CEL to flash every morning if I try to drive it and accelerate before the temperature gauge comes up. It seems to run great though at highway speeds, occ it seems like there is a lack of power but mostly it will kick into passing gear no problem. The only time it ran poorly on the highway was when the problem first occurred, going highway speed on the way to the airport. I didn't think I was going to get to the airport it was missing so badly. I stopped and put a can of oil and gas treatment in and it seems to run ok except for when cold first thing in the morning.

Dave

Bikeman982

Thanks for the inquiry Sorry to say it is still not fixed, a different local mechanic felt that it was a bad coil. I got a new coil and replaced one of the 2 coils. Replaced the coil supplying the no 1 and 4 cylinder as the P0304 code caomes up more frequently than any other cylinder the P0300 is still the most common code by far. The fuel pump will probably be the next thing I replace, but if the fuel pump is bad would it still run good once it gets warmed up? I can reliably get the CEL to flash every morning if I try to drive it and accelerate before the temperature gauge comes up. It seems to run great though at highway speeds, occ it seems like there is a lack of power but mostly it will kick into passing gear no problem. The only time it ran poorly on the highway was when the problem first occurred, going highway speed on the way to the airport. I didn't think I was going to get to the airport it was missing so badly. I stopped and put a can of oil and gas treatment in and it seems to run ok except for when cold first thing in the morning.
Dave

I don't believe it is your fuel pump causing the symptons you mention. Since you have had all the fuel injectors replaced, I would suspect the ECM. The injectors are electronically triggered valves that are controlled by signals from the ECM. An injector is either on or off (open or closed) and there is no variable control other than duration. The ECM is what controls this duration based on numerous considerations, such as timing and advance, EGR functions, and idle speed control. Hope this helps.

Help As expected the fuel pump did not fix the problem, still getting P0300 codes occasional individual cylinder primarily P0304. So far have had new injectors, new fuel pump, new plugs, new wires and coils to no avail. Anything left besides replacing ECM? I can't see any exhaust or vacuum leaks. It runs fine for a minute or 2 when you first start it up in the morning, but if I don't let it warm up. i.e. coolant temp gauge getting to half way, and try to drive to work, it will hesitate on acceleration and the CEL will flash. The rest of the day it runs pretty much fine.

Thanks for any help

Dave

Wow - the only things left are the emissions related and engine mechanical components. Did anyone try and check compression on the engine to see if it is a burned valve causing the problems? You've changed just about everything except for O2 sensors and catalytic converter (emissions side of the problem), the ECM and burned or sucked in valves. Normally this code is just ignored - but any drivability issues means there is something wrong with some sensor - or like you mentioned, could be ECM related.

Yeah compression has been checked and said to be ok, I think I will check it myself. Is it necc. to do a compression leak down test and if so how does one do that?

Thanks

Bikeman982

My suggestion is to do a compression check to verify cyclinders are good. If that fails to turn up anything abnormal, then it would most likely be the ECM. I have removed numerous ones myself (just taking them out at the junkyard looking for another one for the car I am working on). They can also be found at junkyards and on e-bay. Hope this helps.