@ what rpm ?

 

Ya it's walking all over the place.
So while driving it's 1.9-2.6
1.9-2.2​​​​@1600rpm
1.9-2.2@2000rpm
But constantly jumping between these values.
Damm I forgot to get the readings at idle.
The reason I asked about the cam position sensor is because i replaced it with a new ac delco 3 years ago because of this cracking of epoxy as seen here. This is an old cam sensor.but obviously a lot of heat here to make a crack.



So what i think is as soon as I replaced my starter those 100 codes I was getting went away and the truck ran way better which leads me to believe that the electrical system had a short by something in the starter and is was a slow death of that starter. I was surprised. No codes were coming up. It was like trying to find a needle in a hay stack trying to find the problem. As soon as the starter was replaced the codes were gone and a noticeable difference in the way the truck ran It was a hugh difference.So should I take a look at this sensor again and seen if the epoxy is cracked again ? Should i just save the time of looking and just replaced it. Would that be an indication that i need to be replacing because its jumping all over the place?
Is there any difference in Delphi vs ac delco parts ?

Thanks
Jason

 

Delpji or AC Delco should be good.

The more timing chain slack and gear wear you have, the more its going to swing during acceleration and decelleration while driving. I have never watched mine while driving so I don't know if that range is typical but my gut tells me that its OK for a truck of this age. The idle numbers a stable so I think we are good there. Could replacing the sensor help? Never say never but I don't think so.

George

 

Hi George

The mystery continues 🤣

Changed the cap rotor and cam sensor. I set the cam retart to 0.3 because after replacing the cam sensor it was 3.9. The misfiring stays at zero when driving @ idle i see misfiring on #1 and see the odd misfiring on other cylinders but its better then it's ever been. I just don't know why ? When I'm at idle and getting misfiring as soon as im above a 1000 rpm all misfiring on #1 goes away as well as the other cylinders and all cylinders stay zero's. Sometimes everything stays at zero's at idle.I took it on the hwy and it runs good at 100kms but if I go 120kms I get bigtime misfiring on #6 like a 152 misfires and a few misfires on other cylinders but nothing major. Any suggestions that you can think of will be much appreciated at this point. I don't think it's an ecm/pcm problem because I swapped it out last week before I did the cap rotor and cam sensor and it did absolutely nothing. I have never encountered a problem like this that took so much time to correct. I guess I'm just use to working on an engine with a carb. Much more reliable in my opinion. 😅

Thanks for all your help
Jason

 

Do you feel these misfires?

George

 

Oh ya. I think this has something to do with outside temperature because lastnight it was cooler and the truck ran really good. In the morning when I first start it it runs really bad.

 

1. Does the misfire behavior change with a different steady state rpm or with the heavier load of acceleration?
2. Have you checked your TPS by sweeping through the travel range at key on engine off and looking for glitches?
3. Can you graph O2 sensors?
4. One thing you might consider is taping a fuel pressure gauge to the windshield and making sure that you dont have any pressure drop offs
5. At different steady state rpms do fuel trims change dramatically when acting up?
6. Have you done a compression test? You might want to consider Les' dynamic compression test to look for mechanical issues
7. What is the history on the fuel spider?

George

 

I'll try to answer these questions to the best of my ability. So I'll start with question#1. Well like I was saying the misfiring is happening at idle and you can feel it and see it on the scantool but as soon as I accelerate from idle it goes away completely but if I'm on the hwy I get misfiring when I'm doing 100-120kms and it's alot on one cylinder like 158 misfires and a few on other cylinders. Question #2 Is that the TP angle pid ? I just want to makesure im doing this test correctly.Because i just checked it and it stays at 0 nothing happening i changed the Throttle position sensor but with a Chinese one? Just for testing purposes, I still have the original TPS somewhere # 7 can be eliminated because I changed the spider already.

 

I swapped out the tps and it still isn't working. Is there a way to test the wiring ?

 

So misfires are at a steady state speed, not under the load of acceleration?

I don't think the truck will run with zero TPS signal, are you sure that you have the correct pid? Its easy enough to test without the scanner. With key on engine off you have 5v ref and ref ground feeding a potentiometer with the 0-5v variable output on the sense wire that should show a smooth changing voltage throughout the throttle range.

George