samckitt

iTrader: (5)

I have had this problem going on 6 months or so now & no one can seem to have any idea what is causing it. I have not taken it to the dealer yet fearing it will cost a fortune with them trying multiple things to resolve it.


The symptoms:
Misses like crazy until something gets heat saturated, water temp will be at operating temperature & it still run like crap.

I start it in the morning before work & let it heat up so it runs fine once warm. For about 20 seconds after starting it, it will idle fine & then start missing bad, running like it has a big cam in it & it is loping. I am assuming it idles fine when in open loop mode, once in closed loop it starts running crappy.

I have had a Tech2 on it & the only code is something like 3300 or 3030 (can't remember, but it was for a general missfire). Nothing else.

In the past 6 months I have replaced the intake gaskets, fuel pump, fuel filter, plugs, wires, & air filter. In the past year I replaced the throttle body. Nothing changed. I had to change the fuel pump because original one went out.

I have checked fuel pressure & it is fine. Had a friend use the monitoring feature in HP Tuner & says the O2 sensors look to be functioning properly.

Other strange symptoms are if I try to drive it as soon as I start it, I cannot accelerate at all, any little gas I try to give it, it misses & have no power. I can floor it & it won't get out of its own way. Other thing that is weird is it seems as if the RPM level where is misses is related to the temperature of whatever is affected by the heat. The warmer it gets, the higher the RPM will get before it starts missing until it finally goes away & runs fine. Almost like the rev limiter level changes with the temp. Friends have followed me while I am driving it & it misses & they say smells rich.

Please give me any suggestions you can think of.

Thanks.

tool46n2

Believe it or not...... it could be a dirty injector, intake manifold, or filter. I would start with the cheap stuff first. Cleaned my maf, manifold and my truck ran better. Doesn't Hurt. Hope this helps.

samckitt

iTrader: (5)

So last night I get home & look at the MAP sensor on the TBSS intake & compare it to the one on my truck. Same PN, so I swap them out. This morning I start the truck & same results, runs fine for 15-20 seconds then starts running like crap. While it is idleing & running like crap I go look at the exhaust & it is puffing out fine. (Was thinking about the cat). Then I remembered, my truck has 2 cats, runs duals right before the muffler, both go into the muffler & one tail pipe.

One other thing I forgot to mention, in that area between real cold & warm when I can get a little acceleration out of it, it misses worst about the time it changes gears.

tool46n2 - I have changed both the air & fuel filter. How do I clean the manifold?

Anybody have any other suggestions?

Thanks

samckitt

iTrader: (5)

Stopped at Autozone last night to have it scanned. Found out it had 3 codes, but no check engine light came on.

Because: One of the codes was something to do with the check engine light circuit not reading proper resistance. Bad bulb/circuit bad.

03300 (I think) general missfire.

And one for the crank position sensor.


Haven't tried to replace the crank sensor yet.

Blazingz28

iTrader: (5)

Sounds identical to my symptoms when I had to replace #7?(I think) injector. Would start car up fine, let it warm up in winter, then would start misfiring horrible. Eventually got so bad that SES would blink before I fixed it.

samckitt

iTrader: (5)

Mine misses terribly until something gets heat soaked (long after water temp is hot), the would run fine. The warmer it got the higher the rpm could get before it starts missing.

O2Form

Ya know for a guy that wants help you don't even write down the trouble code??? WTH??


YOU HAVE A VACUUM LEAK...deal with it!

samckitt

iTrader: (5)

Sorry, i didn't have the printout with me when I did the last post.

I don't think its a vacuum leak, I have looked all over for it, sprayed starting fluid around & no change in idle.

But here are the codes:

P0336: Crankshaft position sensor condition. The crankshaft position sensor signal is monitored for errors. Probable cause: Crank sensor defective, check connector and wiring to sensor. Check trigger wheel for damage.

P0650: Indicator lamp control circuit fault. ECM has detected improper voltage level on teh MIL circuit.

P0300: Cylinder misfire detected - random cylinders.
Probably cause: Ignition system fault - spark plugs, ignition wires, coil, vacuum leak, injector fault, high or low fuel pressure.

Looked for vacuum leak, didnt find one, changed plugs, wires, fuel pressure is OK.

O2Form

LOL spray all you want nothing is going to change....this aint a carbed sbc engine. I would suggest checking the intake bolts and pcv system for a start.

samckitt

iTrader: (5)

So I have tried to find a vacuum leak with no luck. Today was thinking, "if" it was a vacuum leak, one bad enough that it won't reach 10mph at WOT, how would a leak that big disappear after it gets hot?

lt1pwr1

iTrader: (1)

Ummm, I would go ahead and replace your crank sensor and/or check the wiring to it. Although I would expect it to act up right away you have a code for it and it is missing bad.

Bacon

Id replace the crank position sensor...if thats off then its going to hose everything up and cause random misfires. If it was an injector, you would have a misfire code specific to one or more cylinders.

You could try cleaning the contacts at the crank sensor, but you could also just replace it since its cheap. The temp thing could be bad contacts heating up - itll happen slower than engine temp for sure.

http://www.amazon.com/ACDelco-213-35.../dp/B000C9JXZ2

O2Form

Let me explain something to you, two things happen when the engine get hot.......things move around and seal better AND the PCM uses the O2 sensors to meter fuel. That PCM is going to make that engine run smooth if it can to a point. Check your fuel trims...if they aint 0 to -1 you have a vacuum leak or fuel starvation from blocked injector screens ...fuel filter etc.

looks like you may have other problems too but ya gotta start someplace logicaly and work through it till you get a understanding of what is going on.

example: PO300 car missfired on ALL cylinders cold and hot, pinged and ran terrible, also hard starting. Fuel pump bad, fuel injector screens blocked with rust, FINAL diagnoses was rusted fuel lines fouling the injectors.

example: PO300 car ran terrible till it warmed up, then it ran smooth and perfect. Intake bolts were loose.

example: no codes, no power, engine pinging at part throttle, fuel trims @ +8 %.
Fuel filter was blocked.

You should look at everything then start diagnoses.

You need a good scanner.

Spartan7

iTrader: (7)

So? Fuel delivery type has nothing to do with the way starter fluid works. A vacuum leak would suck that starter fluid into the intake and cause the engine to rev slightly.

OP, I would do as the others have suggested and check your CPS wiring, maybe replace the sensor with a new GM one. A faulty CPS can definitely cause a random misfire. And your MIL code is probably just due to a bad bulb. That code is intended to inform you when there is a problem with that circuit.

Bacon

O2Form is being a condescending douche. While he may have a lot of knowledge on how motors work, theres no need to act like that.

The OP is looking for help and trying to learn. Why try to make him feel like he doesnt know anything? Cant learn anything if everyone wants to cut you down and be a know-it-all.

Let us know how it goes.

LilJayV10

iTrader: (39)

Good posts man. You are an asset to this board.

OP,

Have you checked to make sure your ECT is working properly?

The best way to check for a vacuum leak on an engine with a plastic intake is hook a scanner up to it and watch your STFT's and 02 voltages.

Spray carb cleaner around the intake and see if your STFT's and 02 readings change. If it is leaking your STFT's will go negative.

As mentioned you should replace the crankshaft sensor. Keep us updated.

joecar

When you remove the crank sensor inspect it carefully for damage (getting struck by the reluctor);

and then try to look at the crank reluctor wheel (thru the crank sensor bore, using a flashlight) as someone slowly turns the crank (by the balancer bolt) so you can see if it wobbles;

try to determine if the reluctor lines up correctly with the crank sensor;

with your finger see if the reluctor is loose in any manner;


Check the crank end play (carefully pry the balancer to bring the crank forward and then push it back in, measure the total distance).

joecar

Something else: make sure the balancer is in good condition and not slipping (where rubber meets metal)...

I've seen old wornout balancers cause some weird stuff.

samckitt

iTrader: (5)

yesterday I changed the CPS, ran worse than it did before & would run for like 5 mins & then die & would restart but only run for a second or 2 then die again. I said Fck it for the night & worked on it today. I took the sensor back out & put back in, now it runs just shitty like it did before replacing it. Old sensor was not hit by target wheel, I didn't look in the hole or try to feel it with my finger. Didn't see these posts until now.

Unhooked MAF & ran it, no difference.

Tried a different DBW throttle body, no difference.

Took plugs out & checked compression:
These are plugs from left to right: 7,5,3,1.


2,4,& 8, look like 3,5&7. Plug #6 is about halfway between a clean & a carboned one.


So I take it 1 & 6 are the ones missing.



Cylinder - Pressure (PSI)
1 - 150
3 - 120
5 - 150
7 - 150

2 - 120
4 - 150
6 - 120
8 - (couldn't get the gauge in)

O2Form

I'd pull the valve covers, inspect the valve springs etc and do a leak down test.