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P0300 Misfires and other codes on2001 GMC Jimmy P0122 P0463 P0719 P1122 P1381

Model: 2001 GMC Jimmy Fault Code: P0122 Posted: 2016-05-26 18:28

Hi there, I've got a number of issues on my GMC Jimmy (2001/4.3L), starting with misfiring fault code: - P0300 - Engine misfires - P0122 - TP or APP sensor 1 circuit short/low - P0463 - Fuel level sensor circuit signal high/open - P0719 - TCC/brake switch "B" circuit signal low/short - P1122 - TP circuit intermittent low voltage - P1381 - Cylinder misfire – ABS/PCM serial data Current symptoms: - Extended cranck time. Hard to start, but it eventually starts. - Service engine on – steady. A couple of times only it went intermittent for a couple of minutes. Once in a while the lamp turned off by itself , but not for long. - Rough idle (smooth run at higher rpm, though). - Hesitation at acceleration from idle. - Unburned raw fuel smell at the exhaust pipe - A couple of times I've smelled hot plastic cable insulation in the cabin (not entirely sure if it came from the outside, though). - No stalls in traffic, but once in a while it does not start at all - the board lights go on, but the engine doesn't turn. Then I can’t even hear the fuel pump buzzing. Once, I've popped up the engine hood and the engine started right after. The vibration helped… somehow, so every time the engine wouldn’t start I'd go under the hood and knock/shake things a bit (suspected wire insulation or continuity problems). It always helped… so far, but the “no start” events are now more often and it takes longer to re-start the engine. (Maybe kicking the tires is not a bad thing, after all! ) Work already done: - Replaced the battery (silly!) - Replaced the spark plugs (they were old, but I did not notice anomalies when compared them with each other). - Replaced the spark plugs distributor and rotor (checked spark plug cables by pulling them one by one out – the engine runs as rough in idle as before, no difference to me). - Replaced fuel filter. - Sprayed the cables with water - couldn’t see sparks or smell burned plastic. Note: none of these “repairs” improved or worsen the symptoms. Some history, as I believe it might be relevant to the issues I see now: I’ve got the fuel pump replaced about 2 years ago by a shop. A couple of months later the fuel level gauge started fluctuating intermittently. Six months later the engine service lamp went off. I treated it with injector cleaner a few times. It ran well for about a year, and then engine service lamp went off again. Another 3-4 months of injector cleaner (and other cleaners) did not fix the problem. In fact, it got worse. Perhaps related to the P1381 fault code: the ABS system is not been working since I’ve purchased the car – the fuse has been pulled out by the dealer, as the anti-lock system seems to be broken (it does not break at all when the fuse is back in). Before I get into the sensors… I am tempted to replace (again) the fuel pump. Any suggestions, please?

Related fault codes

P0122P0300P0463P0719P1122P1381

Comments (11)

Anonymous 2016-05-26 19:00

It just happened again: the engine wouldn't crank. I can hear the fuel pump running, though, for a couple of seconds. The board lights on and the head lamps are on either, but the engine doesn't even crank. (None of the "shaking" tricks works.)

Anonymous 2016-05-27 07:18

check fuel pressure then with KOEO observe fuel pressure drop - drops Xpsi in 5min.... The AC Delco plugs? - What were those "anomalies when compared them with each other" ?e a scanner Do you have a scanner - able to read live data? Next work the TPS issue-

Anonymous 2016-05-27 10:55

I might have access to one of those scanners, kev2. I will try the comparison (thanks, didn't know that is possible), as I suspect the issues are related, or at least some of them are. The new spark plugs are Champion Platinum. It made no difference after replacing them, so I don't think it's them. Throttle Position Sensor - I will check as well, thanks! In the mean time I have had a look at the starter relay. I pulled it out and short-circuited the contacts which gave me large sparks at first, and the engine started cranking. I believe that those arcs unjammed the starter. Shortly after celebrating, the engine wouldn't crank again. This time I've tapped the starter underneath of the car, and the engine worked again. I will replace the starter, but this is perhaps a different issue than the misfiring and engine hard starting.

Anonymous 2016-05-27 11:51

Your excess cranking - hard starting - could be causing starter issue... Fuel pressure and above mentioned leak down test as this fuel injected system is problematic.. The TPS - a simple 3 wire sensor need to check return/signal voltage.. use a DVOM. gray wire 5v, black wire is ground, blue wire measure this voltage at idle

Anonymous 2016-05-28 21:55

I see! The starting usually takes 3-5 seconds, though. I have checked the fuel pressure: - cold start - the pump kicks in for 2 seconds and pressure jumps to ~ 56 psi, then slowly drops to ~ 48 psi. - w/ engine running - the pressure stays steady ~ 58 psi. The pump is OK, I suppose. I couldn't figure where the vacuum line is, so I can check if any vacuum leakage. (??) I have replaced the throttle position sensor (TPS) - no difference. I have also cleaned the exhaust gas recirculating valve (EGR) from carbon deposits (as much as I could) - didn't notice a difference in cranking time, or rough idle. Next I am thinking of the fuel pressure/regulator spider. But I've ran injector cleaners quite a few times. Besides, the P0300 fault code indicates "random" misfires, but not one particular cylinder. An active fuel injector tester (AFIT) is quite expensive; I hope it's not that! What else do I need to check? Oxygen sensors, torque converter clutch (TCC) brake switch, pedal position sensor/switch?

Anonymous 2016-05-29 08:14

check the specs, fuel pressure seams LOW esp that drop to 48psi. That suggests to me a 'spider' issue, as the system is all enclosed in manifold checking is tough. TPS - replacing the part does not check the voltages... P0122 & P1122 are voltage issues.

Anonymous 2016-08-22 18:54

Back to square one!! The flotor's arm of the fuel pump was broken (or poorly attached), thus the fuel gauge was basically not working so I decided to replace the fuel pump. Done! The engine cranks lively in a split second. No rough idle, no acceleration delay, engine check lamp off… Only for about 3-4 weeks (!!!), then all the problems went back again, and got even worse. Now after idling at street lights, the engine check lamp blinks for up to 10 seconds, then goes steady again as I drive over 50 km/h (31 mph). Engine stalled on me once or twice. However, the pump intervention seemed to temporarily eliminate the cause of the engine issues. Similarly, when I replaced the fuel filter, the problems disappeared but for much shorter (one day). Can't figure how or what! Checked the TPS voltage: grey wire – 5 V; blue wire – max. 4.3 V. It should be 4.5 V - 5 V, some said (!?). Could that be the issue, though? Did a computer re-boot by disconnecting the battery for a couple of hours. The only code that came back after a couple of days after was P0300. Got an injection spider from an old vehicle, so I may get in there and replace it. But the code says “random misfires” (P0300) which means that no particular hose is plugged. I am wondering if its pressure regulator can create such issue, or… what else!? Vacuum leak - how do I check it? Does it need to?

Anonymous 2016-08-23 12:40

CEL flashes and then steady - what code do you get - JUST P0300? If only that leave the TPS alone for now. those plugs- are on my mind, it calls for AC Delco and those are NOT a superior plug. Why would you have faith in a used spider ? Vacuum leak - spray carb cleaner on any mating surface hose fitting that could be a vacuum leak - if the engine sound chenges RPM etc you have found a suspected leak area. The fuel press regulator is on spider - Check the EGR they are problematic sometimes a carbon spec will keep open. Might want to check fuel pressure again-pressure and leak down... it will "test*" pump, filter, FPR, and injectors in 1 easy test... * not actually test them BUT give a good look at fuel system...

Anonymous 2016-10-29 13:34

Thank you, kev2! Just the P0300. EGR valve: I cleaned the EGR valve thoroughly, and I replaced the gasket (it had some corrosion in between the two holes). I cleaned the gallery with a 2 ft long flexible wire, and carb cleaner. No change, same problems. Fuel pressure: Cold start: 60 down then quickly down to ~ 35 psi Hot start: 58-60 psi while cranking (cranking is getting longer and I have to press the gas pedal to get the engine running). Then pressure stays steady at 55-56 psi in idle or while throttling. Turn the key off: pressure drops (in a few seconds) to ~ 24 psi (!?) and remains for a few minutes like that. It looks to me like there is some leakage, but I don’t know where to look and what to do. Any suggestion, please? Vacuum leak: I sprayed carb cleaner around the air intake and the vacuum hoses (from the vacuum canister to under the battery) - no rpm change. I pulled out the hose from the vacuum canister nipple and played with it (closing and opening its end). The rpm and the fuel pressure changes by an insignificant amount. The rpm should've increased (!!), right? Does it give any clue about the issue? The symptoms seem to be of vacuum leak (rough idle, long cranking, stalling, smelling unburned gas at the exhaust pipe, and acceleration hesitation). But spraying carb cleaner (also propane) did not evidence that. However, last winter I had issues with my hot air, as almost no hot air was blowing into the cab. After rebooting the computer a few months ago, hot air started working (!!). It doesn't get hotter and more pressure with increased speed, though. Does that offer any clues about the issue? More to that "mystery": My back door window got messed up a couple of years ago, as it was unlocking itself after starting the car. Before that, the back door lock was acting funny. After rebooting the computer a couple of months ago, the back door the window locking systems started working fine (!!). I did another rebooting of the computer yesterday. The engine warning lamp came back (steady and flashing), and the back window does not open anymore (!!). Does that seem like a computer problem? There is also some randomness into this story: Sometimes engine starts right away; sometimes there is no acceleration hesitation or very, very hesitating; sometimes engine dies in parking lots while slow driving and taking a curve. If anyone has a magic wand… please direct it towards my truck! A repair shop work may cost double its worth. These issues drive me nuts, but I like it and I want to keep it. Thank you!

Anonymous 2016-10-29 15:10

only 1 code now and that is p0300 correct? flashing is priority That code and a flashing CEL suggests fuel issue, out of abundance of caution check engine oil for excess fuel... You likely have a leakng injector*, look at plugs for a clue - wet black. But upper manifold removal is needed. *the injection system 'spider' is inside the intake manifold problematic and prone to leaking. google - "4.3 spider injector replacement" lots of tutorials

Anonymous 2017-04-11 15:41

Simone & Kev2 after reading this entire post, IM DIEING TO KNOW THE OUTCOME! simone never wrote back after Oct of 2016.... Did he torch the vehicle? I really wanna know is all. Thanks!