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Little back story here. I bought this blazer a few months back. I believe in August. I never noticed the problem at first, but what happens is above 3000 rpm’s the engine just bounces off the tachometer without shifting(it’s quite scary actually, always feel like it’s going to over rev.) I was getting an intermittent P0355 for the CPS. So I started doing research. I replaced the TPS with a slight improvement now it would be able to get to about 3500 rpms, then it would jump. But now it would start to actually shift (albeit a firm “hard” shift.) I thought I heard it pinging when it jumps up(or the timing chains or valves, I can’t tell) so I replaced the fuel filter, cleaned the air filter (K&N it was filthy) and I pulled the CPS on the harmonic ballancer to check for contact. There were no visible signs of contact, so I cleaned it off, and re-installed. Then I performed a CPK variation re-learn procedure. After that the car would drive a lot better. I can hit about 4,000rpms, then it would do the same thing. Sometimes it would shift, and sometimes it wouldn’t. I immediately got a full tank of fuel after this procedure, and after driving home, literally about 5 minutes after I did the CPK relearn, the Check engine light came on again. This time entirely new. I got a P0300, and (2) P0304’s. Random misfires, and cylinder 4 misfires. Also, a hard start condition developed. No matter the temperature of the car. So I performed a tune up. I replaced the cap and rotor(both terribly corroded) and I replaced the wires and spark plugs. All the plugs I pulled were clean with no signs of oil burning. They smelt good too. After that I cleared the code and took the car home. On the way home the CEL flashed again, but then went out. I assumed it was miss fire again. I read the code and got a P0101, for the MAF. I did remove it to gain access to the driver side spark plugs. So naturally, I cleaned the MAF, and cleared the code. It has not yet returned. The hard starting seems to be getting better but I haven’t driven it enough to really know for sure yet. But, now when I drive the car, I can hit 4-4500 RPMs and I still get the same problem. My first ever WOT with this car was yesterday, and I didn’t hold it long enough to see if it would shift, I thought the engine was gonna go. To shed some light, once it hits the certain RPM range it feels as if the trans is in neutral, and never tries to shift. Normal driving is just fine, anything below 4k and it drives perfect. I currently have no check engine lights. I do believe there may be a knock, I can never really tell. I am trying all the cheap alternatives, I can not afford to take it to a shop. I am in the military, and make barely any money.
So, to wrap up. I have received codes P0355, P0300, P0304, and P0101. I have replaced the TPS, fuel filter, cleaned the air filter, cleaned the MAF, replaced the cap, rotor, wires and plugs. I did a CPK relearn. The hard start only occurred after the CPK re-learn. The problem is getting steadily better… But still, the car does not run as it was intended. No I don’t drive it WOT every where, but I need the full power band to pass, and what not. Any help would be appreciated.
Random bits of info.
There are slightly larger tires on the truck than stock, and my speedometer is 3mph slow. I just changed the oil with 5w30 Valvoline Synpower, and a mobile one oil filter. When I bought the car it was 1.5 gallons low on coolant. Don’t know how long it was low before that. It doesn’t over heat, and hasn’t been leaking since then. No moisture on the oil cap, and the coolant looks good. There is no smoke coming from the exhaust. Everything works as it should. The car drives perfect until I get into it. The fan clutch may be going out.
here is a video from before I did any work. I will get a new video of the current state asap
http://s204.photobucket.com/user/pwnthis/media/Blazervid_zps3706ab28.mp4.htmlEdit: There was no build up on the screen on the top of the distributor. Apparently Ionic gas vapors (something the guy at the Auto Hobby Shop we have on base told me about) build up on this screen. Well mine was clean, and clear.
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[quote=”EricTheCarGuy” post=82523]I like the theory of the distributor gear because it does fit a lot of the issues that you’re talking about. Good call Wisetech. Keep us posted on what you find when you remove the distributor. Post pics if you’re able. We love show and tell.[/quote] would that have anything to do with the MAF? Or the Crankshaft Sensor? Definitely going to look at the gear tomorrow after work. Thank you very much everyone.
We’ll I look the distributor out, the drive gear looked fine in my opinion. It was a little worn, but not enough that I’d think it would affect it. I did however clean the top of the distributor with MAF cleaner. Next step for me is to take it to a mechanic I think. I can’t afford the time and money…
[quote=”wysetech” post=82339]As I have been following along reading every ones suggestions I have had the feeling that I have seen at least one of your problems before. Because of my age sometimes my brain is stuck in neutral.
Some of those engines had a problem with the distributor gear wearing badly. This causes the distributor shaft to “chatter” and will cause crankshaft/camshaft correlation problems and the jumping tachometer and misfire codes you are experiencing.You might pull the distributor to see if you can shave with the drive gear teeth. You will need to perform a relearn again after reinstalling it.
[/quote] my drive gear looked nothing like this. They were all still “square” with minimal wearing in the middle of each tooth.
I thought it was worth checking as I have seen it a few times before. All part of the diagnostic process.
[quote=”wysetech” post=82707]I thought it was worth checking as I have seen it a few times before. All part of the diagnostic process.[/quote]it was definitely a good idea. I have no idea where to look from here…
This is interesting what do you all think?
Going to the shop after work. I talked to a gm guy at the auto hobby shop, he said it could still be a crank or cam sensor. Did some more diagnosing. I put the car in first and drove up to about 4500. The tach goes nuts, bouncing back and forth and off 7k but the engine held steady at 4500. The gm guy says the cam sensor controls the tach? Not to sure about that one. What else do you all think. I’m tempted at this point to just throw in a new crank and cam sensor.
[quote=”tonyroc14″ post=82584][quote=”EricTheCarGuy” post=82523]I like the theory of the distributor gear because it does fit a lot of the issues that you’re talking about. Good call Wisetech. Keep us posted on what you find when you remove the distributor. Post pics if you’re able. We love show and tell.[/quote] would that have anything to do with the MAF? Or the Crankshaft Sensor? Definitely going to look at the gear tomorrow after work. Thank you very much everyone.[/quote]
If the timing is jumping all over the place it will effect the MAF sensor readings as well as the crank and cam sensor readings. Another thought that I had since my last post is your timing chain. If the timing chain has enough slack in it, it can cause the same issues and set the same codes. A quick test for this is to remove the distributor cap and observe the location of the rotor. It’s best to start at TDC so move the crank to that position. Then rotate the engine counterclockwise while observing the rotor. If it takes more than 7º of rotation for the rotor to start to move, you have excessive timing chain slack. If that’s the case, you’ll need to replace it and recheck for the problem.
As always, keep us posted.
I will have to take pictures tomorrow. I have to replace a dizzy in a 4.3 Blazer. Random misfires and a rubbing noise from inside the cap. Popped out the distributor and found the gear pretty worn and the top plate (above the gear) worn out. You could lift the rotor about a 1/4″ straight up, the rubbing noise was the thrust of the gear pushing the shaft up. :blink:
[quote=”EricTheCarGuy” post=82786][quote=”tonyroc14″ post=82584][quote=”EricTheCarGuy” post=82523]I like the theory of the distributor gear because it does fit a lot of the issues that you’re talking about. Good call Wisetech. Keep us posted on what you find when you remove the distributor. Post pics if you’re able. We love show and tell.[/quote] would that have anything to do with the MAF? Or the Crankshaft Sensor? Definitely going to look at the gear tomorrow after work. Thank you very much everyone.[/quote]
If the timing is jumping all over the place it will effect the MAF sensor readings as well as the crank and cam sensor readings. Another thought that I had since my last post is your timing chain. If the timing chain has enough slack in it, it can cause the same issues and set the same codes. A quick test for this is to remove the distributor cap and observe the location of the rotor. It’s best to start at TDC so move the crank to that position. Then rotate the engine counterclockwise while observing the rotor. If it takes more than 7º of rotation for the rotor to start to move, you have excessive timing chain slack. If that’s the case, you’ll need to replace it and recheck for the problem.
As always, keep us posted.[/quote] Would the timing chain be an issue at 98,000 miles? I am trying to replace my cam sensor right now, those screws are a pain in the ass. I took a video of it today. I had it held in first gear, and I got it up to 4500 and the tach started going nuts, but the engine stayed steady. Does anyone have a clue what might cause that kind of tach reading? Also at 3000, it jumps up to 3500…
Another interesting thing to note. When the tach jumps around wildly (on confirmed while in drive, transmission trying to shift) I hear a bunch of clicking noises… I don’t know if its the timing chain, or the valves, or something in the transmission. I am pretty sure it doesn’t do this when I have it in 1st gear only…
Thanks for the help guys. I’ll check the timing chain when I have the tools on hand, don’t have a breaker bar, or a large enough socket…
Well. I tried to replace the Cam sensor. I ended up breaking a plug wire (thank god for the lifetime warranty) and I stripped one of the heads on the screws that holds the cam sensor in. So, I bought a new distributor. Installed it, and put everything back together. I noticed that there is no play at all in the new one. Noticeably with rotational play. None at all. Also, there was less vertical play. Anyways, I accidentally switched the 4 and 6 cylinder wires, and thought I missed a tooth on the cam or something with the distributor. But i rechecked my wires and found the problem. Car ran fine after that. Started right up. Took her for a test drive…..No change. So, I am literally stuck here. I really don’t know what else to look at…
I find it really interesting that there is this “clicking” sound coming from the engine when the tach goes nuts. Also, checked the codes this afternoon, all the same. p0101, p0335, p0300, p0304. Was looking at the data on the scanner. The long term Fuel trim for bank 2 was about -3.9 at idle, while bank one was only -.08 That same correlation between bank one and two remained the same through the rpm band. Meaning bank two was always higher that bank 1. Short term fuel trim looked fine the whole time.
I am so stumped… Please HELP!!!
[quote=”Raistian77″ post=82803]I will have to take pictures tomorrow. I have to replace a dizzy in a 4.3 Blazer. Random misfires and a rubbing noise from inside the cap. Popped out the distributor and found the gear pretty worn and the top plate (above the gear) worn out. You could lift the rotor about a 1/4″ straight up, the rubbing noise was the thrust of the gear pushing the shaft up. :blink:[/quote]
[quote=”tonyroc14″ post=82820]Well. I tried to replace the Cam sensor. I ended up breaking a plug wire (thank god for the lifetime warranty) and I stripped one of the heads on the screws that holds the cam sensor in. So, I bought a new distributor. Installed it, and put everything back together. I noticed that there is no play at all in the new one. Noticeably with rotational play. None at all. Also, there was less vertical play. Anyways, I accidentally switched the 4 and 6 cylinder wires, and thought I missed a tooth on the cam or something with the distributor. But i rechecked my wires and found the problem. Car ran fine after that. Started right up. Took her for a test drive…..No change. So, I am literally stuck here. I really don’t know what else to look at…
I find it really interesting that there is this “clicking” sound coming from the engine when the tach goes nuts. Also, checked the codes this afternoon, all the same. p0101, p0335, p0300, p0304. Was looking at the data on the scanner. The long term Fuel trim for bank 2 was about -3.9 at idle, while bank one was only -.08 That same correlation between bank one and two remained the same through the rpm band. Meaning bank two was always higher that bank 1. Short term fuel trim looked fine the whole time.
I am so stumped… Please HELP!!![/quote]
Refresh me, I know you have misfire codes, but do you still “feel” a misfire?
have checked the crank sensor?
I had been chasing this demon for several months on my 2003 blazer 4.3, it started gradually and got worst. I replace distributor with a new aluminum distributor, replaced cap, rotor and wires 3 times. The third set of parts were all ac delco. I kept getting arcing from the wires, mainly the the coil wire. After putting the ac delco wires on it started arcing out the bottom of the coil to the bracket. After thinking on it a day or so it occurred to me that if the coil was firing when the rotor button wasn’t in the position to let the spark go to one of the wires that it was going to go to the easiest path to ground. Since it idle good and ran good until about 2500 rpms it got me to thinking the coil was getting a signal to fire when it didn’t need to. The crank sensor gives the signal to the coil so I decided to make 2 shim washers from some electric motor insulating paper I had, each washer was about .0085 giving me about .017. I pulled the sensor and put them on, started her up and it was like a new truck, no more missing, arcing, tach steady and true. I hope this helps anyone else that’s having this problem and sorry for being so long winded about it.
UPDATE!! Shims are still doing the trick, it’s been about 4 months and still no problems.
ocument ID: 1212710 #02-06-04-059: Engine Runs Rough, Service Engine
Soon Light On, DTC P0300 or P0335 Set (Shim Crankshaft Sensor) – (Dec
16, 2002)Subject:Engine Runs Rough, Service Engine Soon Light On, DTC’s P0300 or
P0335 Set (Shim Crankshaft Sensor)
Models:2002-03 Chevrolet Astro, Blazer, Express, Silverado and S-10
Truck Models2002-03 GMC Jimmy, Safari, Savana, Sierra and Sonoma Truck Models
with 4.3L V-6 Engine (VINs W, X – RPOs L35, LU3)Condition
Some owners may comment on a rough running condition or a Service Engine
Soon (SES) light being illuminated. Upon investigation, the technician
may find a DTC code P0300 or P0335.Cause
The crankshaft sensor may be contacting the reluctor wheel.Correction
Remove the crankshaft sensor. Refer to the Crankshaft Position Sensor
Replacement procedure in the Engine Controls-4.3L sub-section of the
Service Manual. After removing the sensor, inspect the end of it for
witness marks that would indicate contact with the crankshaft. If
contact with the reluctor ring is indicated, then inspect the front
cover for cracking or other signs of alignment concerns. If the
inspection indicates that the cover is causing mis-alignments, replace
the cover. If replacing the cover, then the 0.5mm shim is not needed.If the inspection of the front cover indicates that the cover is not the
cause of mis-alignments, then the sensor should be shimmed. Add one shim
between the sensor and the front cover. If the concern still exists,
then add the second shim. Unless the sensor has been rubbed through the
casing or deformed by contact with the crankshaft, it should not be
replaced.In either case, the crankshaft relearn procedure should be performed
after any repairs.Parts Information
Part Number: 12565102
Description: Shim, 0.5mm thick
Qty: 1-2Sensor Crankshaft Position: as req’d
12562910
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