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97 Chevy s10 miss under load


metalman55
01-15-2010, 11:16 AM
97 Chevy s10 ls
5 spd
2.2l 4 cylinder

Please help!

about 3 weeks ago i put gumout fuel system cleaner into a full tank of gas. it didn't take long for it to start popping here and there, but this has been normal with other vehicles i have added fuel system cleaners to so i didnt think much of it. it slowly got worse and worse, until whenever the engine is under a load it hesitates, pops, and misses (SES light) in only cylinder 1 (had codes read). i added 2 bottles of chevron fuel injector cleaner (recommended by guy at autozone) and still no change. i changed all the spark plugs, spark plug wires, fuel filter, checked the coil packs, and still has the same problem. it now misses when idling as well but sounds better when being revd. i took it to a mechanic and after a 1.5 hour diagnosis he couldn't find the problem. he checked the fuel injectors, coil packs, fuel system, and a bunch of stuff with his big fancy code reader and confirmed that cylinder 1 was the only one missing and everything else checked out. he also did a compression test and it checked out. I'm about to take it back and do "exploratory surgery" on my engine since i can't afford to pay somebody else to. before i do i wanted to see what some other people had to say about it. please help this determined college student out!"

old_master
01-15-2010, 04:06 PM
Sounds like it could be a coincidence, but maybe not...

Did the technician tell you if it was a rich misfire or a lean misfire? That alone will give us a head start on where to start looking for a problem. It can be determined if the technician knows how to use his scan tool. With out this information, we've got to start from scratch.

What brand and part # spark plugs?
What brand and part # wires?

metalman55
01-15-2010, 05:47 PM
Sounds like it could be a coincidence, but maybe not...

Did the technician tell you if it was a rich misfire or a lean misfire? That alone will give us a head start on where to start looking for a problem. It can be determined if the technician knows how to use his scan tool. With out this information, we've got to start from scratch.

What brand and part # spark plugs?
What brand and part # wires?

he didn't say, however the code that came up was p01301. i just picked up the truck and drove it home without much problems. he said to check the valve springs, and if its not that than it could be a bad driver in the computer system and could require it to be flashed or replaced entirely. he also pointed out that it only misses when idling cold or when under a load.

duralast ignition wires (4636)
ACDelco plugs (41-928)

old_master
01-15-2010, 07:39 PM
P0301 is in fact a miss on #1 cylinder. Aparently he didn't check O2 voltage in the freeze frame data, (that would indicate a lean or rich mixture when it missed). A lean reading would indicate the injector is not opening. A rich reading could mean the injector is stuck open or an ignition problem.

There are two ignition coil packs on your engine: One coil fires cylinders 1 & 4 and the other coil fires #2 & #3. When a coil fires, it fires both cylinders simultaneously. When one cylinder is firing on the compression stroke, the other is firing on the exhaust stroke. It is entirely possible for half of a coil to fail.

Here are some things to try that will narrow the problem down, but, they must be done in this order:

The first two steps will determine if a spark plug or a plug wire is faulty.

1. Swap #1 & #2 spark plugs, if the miss moves to cylinder #2, the spark plug is faulty.

2. Swap #1 plug wire with #2 plug wire and see if the miss moves to #2 cylinder. If the miss moves, the plug wire is faulty.

This step will determine if the coil is faulty:

Only at the ignition coil, (not the spark plugs) swap #1 & #4 plug wires. If the miss moves to cylinder #4, the coil is faulty.

If the miss stays on cylinder #1 after all this, the problem is with either the injector, the wire harness to the injector, or the ECM.


Post your results.

metalman55
01-16-2010, 12:00 AM
P0301 is in fact a miss on #1 cylinder. Aparently he didn't check O2 voltage in the freeze frame data, (that would indicate a lean or rich mixture when it missed). A lean reading would indicate the injector is not opening. A rich reading could mean the injector is stuck open or an ignition problem.

There are two ignition coil packs on your engine: One coil fires cylinders 1 & 4 and the other coil fires #2 & #3. When a coil fires, it fires both cylinders simultaneously. When one cylinder is firing on the compression stroke, the other is firing on the exhaust stroke. It is entirely possible for half of a coil to fail.

Here are some things to try that will narrow the problem down, but, they must be done in this order:

The first two steps will determine if a spark plug or a plug wire is faulty.

1. Swap #1 & #2 spark plugs, if the miss moves to cylinder #2, the spark plug is faulty.

2. Swap #1 plug wire with #2 plug wire and see if the miss moves to #2 cylinder. If the miss moves, the plug wire is faulty.

This step will determine if the coil is faulty:

Only at the ignition coil, (not the spark plugs) swap #1 & #4 plug wires. If the miss moves to cylinder #4, the coil is faulty.

If the miss stays on cylinder #1 after all this, the problem is with either the injector, the wire harness to the injector, or the ECM.


Post your results.

the mechanic said that all of the fuel injectors were pulsing correctly, even when it was missing. the miss did not move to cylinder 4 when i switched the wires. i ordered a new ECM today as i have now heard that from multiple sources. I will post results after i replace it.

old_master
01-16-2010, 09:19 AM
The ECM fires the injectors sequentially, (no two fire at the same time). If he said they were all pulsing correctly, chances are it's not the ECM. Make sure you can return it if that doesn't fix the problem. (This is the importance of proper diagnosis)

Did you do the first two steps? They make sure the plugs and the wires are good. Swapping #1 & #4 plug wires, and the miss stays on #1, the injector is not firing, BUT, you need to know the plug and wire are ok. If the plug or the wire is faulty on cylinder #1, the miss will stay on cylinder #1. After each of the tests I mentioned in the previous post, you need to re-set the OBDII and drive it until the SES light comes on. The ECM will tell you what cylinder is missing.

metalman55
01-23-2010, 12:10 PM
I found a sloution! i should have stuck with my first instincts. i took the truck down to jiffy lube and paid 70 bucks for their fuel system cleaning and the truck has been running better than when i got it! must have been a very stubborn clog in injector 1.

thanks for the help anyways, hopefully these posts help somebody else out. they are usually where i get a lot of my information on things i don't know a lot about. its so great to be able to have people willing to help those who need helping.

metalman55
01-25-2010, 09:09 PM
okay, so after a couple days of running fine, it went right back to doing the same thing. total bummer. so i removed the fuel injectors to take them in and have them professionally cleaned, and i couldn't help but notice that my intake manifold was coated in a thin layer of black gunk that seemed to be coming out of cylinder 1 (goes into the other intake pipes progressively less as you go towards #4). not only that, but there are shiny silver metal shavings in the cylinder 1 intake. this combined with the cylinder 1 missfire, and hesitation under load like i mentioned before. what do you think?

old_master
01-25-2010, 09:24 PM
The carbon deposits are from EGR... perfectly normal. The metal flakes...hard to say without seeing them but possibly from the injector???

metalman55
01-25-2010, 10:17 PM
The carbon deposits are from EGR... perfectly normal. The metal flakes...hard to say without seeing them but possibly from the injector???

nevermind, not metal shavings. upon further inspection it was just the poor lighting. chunks of gunk built up to look like metal shavings. i am goingto take the injectors in tomorrow to have them serviced. as far as all of the black crud, how should i go about cleaning it?

old_master
01-26-2010, 02:27 PM
You can use a scraper to loosen the big chunks or a wire brush. pick out the big chunks and use a vacuum to clean the rest out. Don't use Mom's good vacuum, she'll get pissed, guaranteed!

metalman55
03-03-2010, 03:01 PM
okay, so here is the update.

It no longer misses, it only missed like once or twice in the beginning of the problem but hasn't since. found out the "popping" noise was the engine backfiring. sounds like unburned fuel igniting in the exhaust manifold.

I had the fuel injectors serviced to specs at a specialized shop. didn't help. cleaned the intake plenum and the gunk, didn't help. changed a couple vacuum lines (the ones to the weird black mystery ball attached to the hood) helped for a few days but same problem gradually came back. checked the fuel pressure, its within specs according to my Haynes manual.

I changed the crankshaft position sensor and its been a week and a half (about 15 key cycles of decent trips) and the computer still has not learned it. the code comes back right away after cleared. thinking of replacing TPS next, or even coil packs. probly coil packs first. any other ideas?

old_master
03-03-2010, 03:12 PM
What DTC's are in memory and what order are they in, (first to last)?

metalman55
03-03-2010, 03:15 PM
the codes? im not sure. the only codes that have come up are the one from cylinder 1 missing from the beginning, and then the crankshaft position sensor not learned, then i just had that cleared at AutoZone and it came up right away again.

old_master
03-03-2010, 03:30 PM
If a DTC comes right back after clearing them, the problem is not fixed. DTC's never tell you that a part is faulty, they tell you what circuit a problem has occured in. Find out what the DTC was, then post it here and we can diagnose the problem.

metalman55
03-03-2010, 04:26 PM
If a DTC comes right back after clearing them, the problem is not fixed. DTC's never tell you that a part is faulty, they tell you what circuit a problem has occured in. Find out what the DTC was, then post it here and we can diagnose the problem.

alright, i got the code checked again. it is P1336

old_master
03-03-2010, 05:26 PM
P1336 "Crankshaft position system variation not learned" must be performed with a bi-directional scan tool. The run of the mill scan tool is not capable of performing the relearn on the 2.2L engine. I can email you the procedure if you need it, but most shops will have it.

metalman55
03-03-2010, 05:31 PM
P1336 "Crankshaft position system variation not learned" must be performed with a bi-directional scan tool. The run of the mill scan tool is not capable of performing the relearn on the 2.2L engine. I can email you the procedure if you need it, but most shops will have it.

alright, doesnt sound like theres a way around takin it into a shop for that. what do you think my chances are of this fixing the hesitation/backfire problem? any other ideas about that?

old_master
03-03-2010, 06:15 PM
If there are any other DTC's, other than the P1336, they must be diagnosed and repaired BEFORE doing the relearn. Did you do all of the steps, in order, in post #4.

metalman55
03-04-2010, 09:59 AM
If there are any other DTC's, other than the P1336, they must be diagnosed and repaired BEFORE doing the relearn. Did you do all of the steps, in order, in post #4.

no other codes that the guy from autozone told me. i did do the tests. it wasnt missing but i did them anyways. switching the plugs it still worked fine, switching the wires on the plugs made it idle horribly but i dont think any other codes came up (last time a code came up while there was already one the ses blinked and it didnt this time). i didnt get a chance to change the wires on the coil pack yet.

im taking it to a shop monday to have the relearn procedure done, then it sounds like ill have to drive it around for a week or 2 unitl it learns it. its a different guy from the first time and he has way more equiptment and better code readers so i might bring it back for a couple hours of diagnosis but he was sayin that he wouldnt let me have him diagnose it than me work on it more so im probly gunnu have to pay the guy an arm and a leg. anyways, ill keep the page updated.

old_master
03-04-2010, 02:24 PM
....switching the wires on the plugs made it idle horribly....

The reason it idled horribly is because you had the plug wires crossed. You need to swap entire plug wires from cylinder #1 & #2, not just at the spark plug end. If P0302 is set, the wire that is on cylinder #2 is faulty. If the P0301 still sets, move on and do the coil test.


....im taking it to a shop monday to have the relearn procedure done, then it sounds like ill have to drive it around for a week or 2 unitl it learns it....

When the relearn procedure is performed correctly with a scan tool, the relearn is done immediately. Don't let him buffalo you into thinking you have to drive it around for the ECM learn it. That's the reason for the procedure, to force the ECM to relearn.

metalman55
03-17-2010, 10:46 AM
okay, so the solution was found by the mechanic. i probly wont be taking anything back to him though. apparently it took him 6.5 hours and an expensive phone call to fix it. he wasnt very clear on what the problem was exactly but im pretty sure he said one of the coil packs was slowly failing. what really sucks is that was the next thing i was goingto change. he also put a used pack in and never called to check if i wanted him to put a new one in. i probly would have had him replace both of them with new ones, but oh well.

all in all, i would have been able to fix it sooner thanks to the help here if it was giving me a missfire code to do the tests with. or if i changed the coil packs instead of the cps (still frusterated that my hanes manual says nothing about a relearn procedure). but the truck now runs smoother and stronger than it has in a long time! thanks for the help and info master

old_master
03-17-2010, 03:07 PM
Wow! One more step and you would have found it. Oh well, glad you got her fixed.

shaunst
03-31-2010, 01:32 PM
I have a 1999 S-10 2.2L 5M with a similar problem. I recently bought the truck with no apparent problems. It has 125,000 miles, so i decided to change out plugs, fuel and air filters. After doing that and sitting in line to get emissions done CEL came on, code was P0301. Checked plugs and wire connections, reset computer, same code in about the same amount of time. I swapped plug wire #1 and #2, reset computer and P0301 came on again. Next step i was going to swap the coils around but i read in here how you suggested just swapping #1 and #4 at the coil. Will this also work in the 1999 (i'm thinking it will). Thanks for any help.

old_master
03-31-2010, 03:47 PM
Swapping 1 and 4 at the coil will work on 99 as well. The only thing you have determined so far is that both wires are good. You'll have to do the ENTIRE procedure EXACTLY as outlined in post #4 to determine what's causing the misfire. You're using the ECM to pinpoint the problem by giving it good information in different places. Depending on where you put the "known good" information and the ECM's reaction, the cause can be determined. There are several things that can cause the problem you're looking for: spark plug, plug wire, ignition coil, injector, ECM and/or injector wiring. You "force" the information where you want it, the ECM gives you a result.

shaunst
03-31-2010, 04:58 PM
I've also switched the plugs, so the next step would be the coils. Thanks i'll give that a try tonight.

old_master
03-31-2010, 07:36 PM
Only at the ignition coil, (not the spark plugs) swap #1 & #4 plug wires. If the miss moves to cylinder #4, the coil is faulty.

If the miss stays on cylinder #1, the problem is with either the injector, the wire harness to the injector, or the ECM.

shaunst
04-03-2010, 04:46 PM
swapped #1 and #4 at the coil. Reset computer, and after about 20 min of city driving code came back on P0301. So looks like the injector is next.

old_master
04-04-2010, 03:27 PM
Could be a partially clogged injector, a faulty injector, a poor connection between ECM and injector, or a poor or loose connection in B+ (pink) wire to the injector. It could also be a vacuum leak to #1 cyl only, or a mechanical problem in the valve train.

shaunst
04-05-2010, 02:32 PM
Well the injectors are impossible to get to. They don't look to be as easy to access as the earlier design of the intake manifold on the 2.2L. Do you have a break down on diagnosing the other things you said could be wrong? I'm trying to do the easiest first.

michaelcannon88
04-06-2010, 01:49 AM
little info i havent used gumout to clean my system doesnt sound like i will i stick with what I kno and SeaFoam is the way to go might be pricey for some but man it works had so much gunk and clogs in vacume fuel system and brake system that just runnin 1/4 of a can into intake and brake booster and full can in full tank of gas fixed right up ran for 40k miles till i finally started having the typical 4.3 censor and electrical problems.

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