1999 Chevy Blazer Please Help! Getting very Frustrated! B

JKHAMISTOS

MEMBER
1999 CHEVROLET BLAZER
6 CYL
4WD
AUTOMATIC
197,000 MILES

Hello,

My 99 chevy blazer 4.3 v6 has been giving me trouble. I have a hard time getting it to start and when it does start it idles really low, stumbles and dies, unless I lightly push the gas pedal and the engine slowly revs up, but my rpm gage is not working. If I get it running long enough and put it in drive it kills. I had it scanned and the only code that comes up is p1351 Ignition Coil Control Circuit High Voltage, and I cant find a straight answer online so far.

I have replaced the starter, pick up coil, ignition module, rotor, plugs, plug wires, distributor cap, map sensor, air filter, fuel filter. I checked the entire engine for vacuum leaks and repaired the ones I found and cleaned and checked the pvc. I checked the egr system and its good. I checked the coil and its firing good and checked it with an ohmmeter. I checked the fuel pump and the fuel pressure and its good. I cleaned the air intake system and did an oil change. I had the catalytic converter checked and its good. My transmission is brand new only 1 year old and its good. My MAF sensor is good. The engine timing is correct and the timing on the distributor. I checked the wiring that I got from the diagram for that p1351 code and I cant find a problem.

So I would be very grateful for some answers. I wish I knew the answer. The only thing I can think of now is the PCM, cause a mechanic said he was so sure that my no start problem was coming from my computer, so he took mine off and went to the junk yard and put a used one on and this was before I had replaced anything or checked anything yet. I just got the security light to go off by doing the passcode thing the dealer told me to do and then it started but only after I replaced the ignition control module and cam sensor. But I think it funny how my rpm gage doesnt work anymore. And now I cant get my old pcm back, cause the guy scewed me. But it is the right pcm.

11 Replies

ZACKMAN

MECHANIC
4,202 POSTS

Here is the diagnostic for P1351. VCM is your computer. Prior to running the diagnostic, make sure that your crankshaft position sensor is in good order.

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Tuesday, March 24th, 2009 AT 10:11 PM

JKHAMISTOS

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I replaced the crankshaft sensor. I used an ohmmeter and checked all the wiring and nothing is wrong that I can find and I am stumped. I dont know what the problem is.

It starts. But it idles really bad and then it kills. If I press the gas pedal too hard it will kill. If I press the gas pedal lightly, the engine slowly catches up with me and revs up. Sometimes at idle, it will act like its going to die, but then revs up by itself. If I put it into drive or reverse it kills.

The RPMs do not work.

I replaced the starter, plugs, plug wires, distributor cap, rotor, ignition module, camshaft sensor, crankshaft sensor, MAP sensor, fuel filter. Checked and cleaned the air idle control valve and sensor, checked the throttle control sensor, cleaned the egr valve and pcv, patched up all the vacuum leaks I can find, oil change, radiator flush, checked and cleaned the MAF sensor. Checked the fuel pump and fuel pressure and it is good. I also checked and double checked to see if the timing was correct and it is correct by the book.

I scanned it with a scanner too.

Here are the codes:

P1351 Ignition Coil Control Circuit High Voltage
P0140 Downstream heated o2 sensor circuit high voltage(bank1, sensor2)
P0108 Manifold Absolute Pressure sensor circuit high input. (I keep getting the code, but I already put 2 new MAP sensors in it with in the last week, and I still get the code)

I know that the O2 sensors are bad, but I should still be able to drive it. Some mechanic told me the other day that my catalytic converter could be the problem. He told me to take out the O2 sensor after the engine before the cat, and if it was the problem I would be able to drive it. But still I have a problem. I did tap on the converter with a rubber hammer and I heard rattling.

Please Help. I hope this is enough info. I have a 1999 Chevy Blazer 4.3l 4wd V6 Enhanced Distributor Ignition.

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Wednesday, April 1st, 2009 AT 8:58 PM

ZACKMAN

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Diagnostic steps for P0108 is VERY similar to P1351. They both refer to the connection to the sensor from the VCM. Either the connection is intermittent (loose harness), poor, or no connection at all. High current means either no connection from the VCM or open circuit (broken wire). I would urge that you follow the diagnostic steps one by one. Be sure that you have a good digital multimeter for the process.

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Thursday, April 2nd, 2009 AT 11:19 PM

JKHAMISTOS

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I cant find any diagrams for the P0108 MAP code.

Do you have one? I need to know what wires and what color harness on the PCM and what number wire? Other wise it would be a huge guessing game with trying to find out the MAP sensor wiring.

I have the book, but it doesnt tell me what color harness on the PCM and what number slot on the harness, it just tells me the color of the wires and there are many same color wires.

I checked the wires from the PCM to the Ignition module and they are good. And the harnesses on the PCM are good and all the pins are straight.

I also checked the wires from the crankshaft postion sensor. The input wire, number 31 the yellow wire is good, but the ground wire number 28 has infinite resistance. Does this mean there is a problem with that wire and could it be my problem?

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Friday, April 3rd, 2009 AT 1:16 PM

ZACKMAN

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Friday, April 3rd, 2009 AT 9:24 PM

JKHAMISTOS

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What color harness on the PCM is the MAP sensor wires located? And what number wire is it on the harness?

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Saturday, April 4th, 2009 AT 11:28 PM

ZACKMAN

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Sunday, April 5th, 2009 AT 10:51 PM

JKHAMISTOS

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All the wires are good. Im going to replace the PCM and the cat converter w/ O2 sensors. I hope it helps. If it doesnt then I dont know what to do. I keep you posted.

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Tuesday, April 7th, 2009 AT 10:42 AM

ZACKMAN

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Keep us posted.

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Tuesday, April 7th, 2009 AT 10:20 PM

JKHAMISTOS

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Here is an update.

I just put a new programmed PCM on this morning. When I put it on, my Blazer still would not start. I got so upset that I just said screw it and had it towed to the dealership so I can find out once and for all what was wrong with it.

He plugged it up to the Tech 2 scanner and ran some tests. The PCM was good. He then pulled my plugs out and cleaned them and it started but very unstable. Then a code for the camshaft sensor came up. It turned out that the new sensor was bad and my old sensor was good. The old PCM was bad too. Well, after putting the old cam sensor back in, my vehical started, and the RPMs came back on and would idle fine and I could drive it.

He checked the fuel pressure and it was good. Here is the thing that I have to figure out. He said the Tech 2 detected misfire in cylinder #4 and #6 and no other codes. He wanted to run more tests but I didnt have any more money. He also told me that those same spark plugs on #4 and #6 had coolant in them. He advised me not to put a new Cat converter or O2 sensor on, because he said until the misfire is fixed the new O2 sensor and converter will just mess up again. He said that everything checked out good except the O2 sensors, converter, and the misfire.

I did have to replace the head gasket and water pump in Jan. I am no longer overheating or losing coolant. I drove it around all day today and the only thing I noticed was semi rough idle, it only starts on the 3rd try, hesitation uphill, poor acceleration.

So this is where Im at. What do you think? What could cause the misfire?

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Friday, April 17th, 2009 AT 2:12 AM

ZACKMAN

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I can understand why the tech say not to replace the O2 sensor and cat. But based on the P0304 and P0306 diagnostics, if the CEL is blinking, there is a problem with the catalyst system. I cropped a part of the diagnostic.

Step #11 bothers me a bit. When you replaced the head gaskets, did you do a compression test or a leak down test? Just to make sure the block isn't cracked.

I had a similar problem with a Park Avenue right now. It turned out that the intake manifold is cracked.

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Tuesday, April 21st, 2009 AT 10:55 PM