engine cutting out/missing

I am having a problem with my engine missing under hard acceleration at higher rpms. Have not noticed any problems anywhere else except when accelerating hard in the upper rpm range. I watched my fuel pressure and injection pressure today and they were both holding good while engine stumbled. I was thinking maybe the IDM or cam sensor??? Anyone with some ideas?

Chris

MAP sensor my guess

I never thought about that. How can I test to make sure that is my problem? I can look at the reading through my Areoforce Scangauge and see what the pcm is seeing?


Chris

Try another one is my guess. But usually have to buy on to do that

Thanks next time I am around someone with a OBS i will swap them map sensors and see if that helps, hate to go buy one till I know its the problem. I think tomorrow I will trade out the IDM with my spare and see what that does. I may also throw a new cam sensor in if the IDM does not help. Stay tuned!!!

Chris

This is not at a shift point right?

MAP sensors aren't cheap

No it is not at a shift point and it is not to the rev limiter either.

Chris

ytee said:

No it is not at a shift point and it is not to the rev limiter either.

Chris

Click to expand...

I think this will be interesting to wee what is going on.

Today I installed my spare IDM and went for a ride. I also set my Scangauge to read the boost that the MAP sensor was seeing. Everything looked as normal until I had the engine warmed up and I stood on the throttle, at about 29-30 psi the Scangauge started showing 2-4 psi at the same time the engine started missing/cutting out. My question now is do I just need to regulate the boost the MAP sensor is seeing or do I need a new MAP sensor and regulate what it sees? Years ago I had a boost fooler and could not tell the difference with or without the fooler so I took it off. With my new motor I see a little more boost, probably around 50 psi.


Chris

I still say the MAP sensor could be the problem. Try to find a spear or borrow one.

I definitely agree the MAP sensor is my problem. I just need to figure out if the sensor is trash or I just need to regulate what boost it is seeing.

Chris

I installed a fooler on the MAP line today and set it so the cpm is not seeing more than 23 psi, verified by the Scangauge and now engine is running fine with no stuttering/missing.

Chris

Nice to see someone coming back to post the solution. Interesting where the threshold was for problems.

Tom what I don't understand is years ago I had a fooler on the MAP line and didn't ever see a difference with or without it, no miss. That same MAP sensor would see 35-38 psi on a reg. basis with no problems. Now right over 30 psi. is where the miss would start at the same time that the boost reading on the Scangauge dropped. These trucks sure can be weird sometimes!!!

Chris

I purchased a boost fooler today, i was having the exact same issue as you.

Hope it solves my problem as well

Chris, I'd play with that threshold a little. I know on Cale's website, he has a specific psi for the OBS trucks and I think it's over 30. You might tweak it little by little to get the peak boost that the map "can" read.

I believe Cale told me it is close to 35 psi. when you will have problems, but he also said the cpm is sending max fuel in under 20 psi.

Chris

Good to know. I've got a fooler on mine that was set for the SD I used to have it on. Around 20 I believe. Was going to adjust it higher to see if it helped with fueling any.

around 17-20psi the PCM is fully fueling, so turn the boost fooler up shouldnt change much. This is why Dieselsites fooler cant even be adjusted, cuz it doesnt need to be