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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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I am so lost! All of these problems I have have seemingly appeared out of nowhere. I had a random, and very intermittent p0335, and I tried to alleviate the problem and I opened up a can of worms!!! By replacing the fuel filter, and doing a Crank Variation relearn, I seemed to have destroyed my fuel pressure regulator, and caused a random misfire (which I do not see, or feel, ever)In the search of the problem, which started out as a p0335 and a jumpy tach, and turned into a hard start, bad fuel mileage, random misfire problem I have replaced about 600-700 dollars worth of parts.
I replaced the TPS, cap, rotor, plugs, wires, the entire distributor to include the cam sensor, and the coil. Did not change one thing. I replaced the plug on the CKP, and then I ultimately replaced the CKP, that finally alleviated my jumpy tach (for future reference the CKP controls the Tachometer, not the coil)
I got an idea for my hard start condition after I tried to use some starting fluid and it created no difference. I started the car in auto flood clear mode (which is flooring the pedal while cranking, it shuts off the injector pulse) and the car still started. If I held the pedal down the car would die after about 2 seconds. So I started chasing a fuel leak. I did a leak down test and found that the pressure in the rail dropped to about 35psi after 4-5 minutes. Without further investigating the issue (all the proof I needed and i wanted to replace the whole unit even if it was just the FPR) I bought a new fuel spider. When I took the intake off, much to my relief there was copious amounts of fuel all over the back of the intake. That car no starts instantly, and runs great…. But alas, the P0304 has returned, and is still prevalent.
The number 4 cylinder has a second, brand new wire on it. I am going to pull my ICM off and reapply some thermal paste, and then if that doesn’t do it I am going to replace all the wires again. I have moved spark plugs around with no change. The cap and rotor are quality AC delco parts. However the wires are not. I could not afford the 110 dollars at the time. However, when I look under the hood at night I see no arcing. The only thing in the ignition system that hasn’t been replaced is the ICM.
Second question. How important is the different modes of MIL? Meaning flashing or staying on constantly. I know if it flashed is means there is a misfire, or something wrong with the air metering. But before my CEL would constantly be on, and then it would flash and stay on after it flashed. Now it just flashes for like a minute goes out, and flashes again for a minute. But still the same code. P0304 Also, freeze frame data showed that the fuel trims were not exactly perfect. One was like 7.4 the other was like 3 or something. I don’t exactly remember, maybe I’ll have to look into that. Would that lead me to the O2 sensors?
Anyways, I am looking for all the help I can get. I have absolutely no drive ability issues, it will wind all the way up to redline and shift perfect, starts and idles amazing. I just want that damn CEL to go away forever!!!
HELP! 🙁
Also, freeze frame data showed that the fuel trims were not exactly perfect. One was like 7.4 the other was like 3 or something.
That is actually okay, anything less than about 10% is okay and not causing your problem.
I still think you need to test for timing chain stretch.
The ECM can compensate for timing chain stretch, but you still will get weird random misfire codes.
So then the only thing left to look at is mechanical? 🙁 I will have to check the timing and compression then. However, is it odd that this misfire occurred as soon as I did the fuel filter, and CKP variation relearn? Or could it just be coincidence.
[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]
Checked compression and timing chain slack. Compression was between 190 and 195 on ALL cylinders.
Running PSI for cylinder 4 was between 60-100 psi. Cylinder 2 was 60-105 psi, and cylinder 6 was 60-100 psi
Cylinders 1,3 and 5 were all between 60(at idle) and 100 at about 1500 RPM.
There was ZERO noticeable chain slack.
After these results I would say it’s safe to bet that the mechanical operation of my engine is in fact in good condition. Maybe I should replace my wires again?
I am going to mount my go pro in the engine compartment and drive it around at night to see if there is any arcing. I can’t see any at idle and while reving the engine, but maybe under load there is.
Couldn’t find any electrical loss, so now I’m at a loss. I feel that it is definitely running rougher at idle than it ever has…
I’m trying to go back in time. The first time p0304 showed up was immediately after I replaced the fuel filter, and the crank variation relearn. I’ve checked my fuel filter for leaks, and I have good pressure at the fuel rail, so that should rule out blockage. Maybe the crank variation relearn had something to do with it? One mechanic I spoke with told me he has experience with cheaper quality diagnostic computers actually alter the pcm when he tried the relearn, actually removing the rev limiter from the vehicle he was working on. Could something similar be happening here?
Anyone have any idea whats left to look at? I had a friend with a tech2 scan it and it showed the MAF was out of specifications, so we replaced that. Now it’s in specs, but still nothing. I swapped all the plugs again for new ones, and swapped them from cylinder to cylinder. I also replaced the wires again with quality Bosh ones. I rechecked the compression, and cylinder 4 was at 170psi, while the rest were at 180-185. I honestly can’t see that as my cause, but at any rate I am going to run a leak down test and see if there is any leakage. I couldn’t image there would be with compression like that. I have good spark on all the wires, but I still think I am going to get a spark tester and see what I get. I am so stuck… 🙁
Soooo. I did a leak down test on the passenger side bank. 2-4-6. It returned near flawless results. I had less than ten percent compression loss on the whole bank. Plus, I could barely hear air escaping past the rings… ZERO wind noise in the intake, exhaust, or anywhere else. Just through the oil dipstick tube, and the oil fill. I had to use a piece of rubber hose to even hear the air escaping through there. Checked spark with a spark tester, and its good. I also checked my fuel pressure, this is where I might be leaning towards next. It was only about 50-52 psi at idle. If I remember correctly it should be around 58psi…
With the key on engine off, and the fuel pump on the pressure is 60psi, as soon as the pump turns off it drops to 58psi immediately. Another thing I suspect is the fuel pressure regulator… again. I get a few weird starts every now and then, and the car started when I was in flood clear mode. Going to pop the intake off this weekend.
my three suspects as of now are
1. My ECM
2. Fuel Pump
3. FPRNEED HELP
Not sure why the ECM is on the list. I doubt you’ll get anywhere with that. A 2psi drop in fuel psi is not significant. So I don’t think your fuel pump is at issue. To check the FPR, remove the vacuum hose at idle and observe the fuel psi reading. If it goes up, then the FPR is working correctly. Also check for fuel in the vacuum line. If there is any, replace the FPR and recheck for your problems. The 170psi compression on cylinder 4 is significant however. 10psi lower than the rest. An engine needs to have balance. If it’s out of balance it won’t run smooth. Compression loss on one or more cylinders can cause this. Engine mechanical is so often overlooked. Remember that an engine is an air compressor. All the other stuff is just there to make it run. If the mechanicals aren’t right, nothing is right.
ECM is in the list because this all started when I did a CKP variation relearn… Seems plausible to me.
The FPR is located in the intake manifold, only way to test it is with the engine off, and intake removed….so I’m just hoping I didn’t see fuel in the intake.
Fuel pressure is also a concern. When this all started I did the CKP variation, and while I was at the shop with the computer, I replaced the fuel filter. My tank was pretty empty, and I pulled the relay and ran the engine to relieve some pressure. Anyways, took a while to prime the system after that. A little worried I might have messed up my fuel pump?
Also, everything I read I’m fuel pressure should be between 58-62psi? Not sure how accurate that is.
Lastly, is 170 from 185 really that significant? I was under the assumption it had to be 15% or more to affect the engine?
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