Today my truck hiccuped a little. It was wierd, about 38 miles an hour and probably 1200rpms. Slowing accelerating and it hiccuped. I got home tonight and threw a reader on it and came back with 1247=low boost level???
Does anyone know what detects boost levels and sends them back to the pcm? I dont think theres a problem with my turbo cause my isspro boost gauge is showing normal levels. I went back to an older black cps a couple weeks ago but i dont think this has anything to do with it. And replaced my IPR about 6 months ago. Any thoughts FTEs?

 

Map sensor maybe, are there any symptoms to a dying map sensor or do they just die? I know they can be fooled for overboost but anything for underboost?

 

MAP sensor would be the thing that sends the boost info to the PCM

DTC P1247 or P1248 indicate turbo boost pressure was low or not detected.
Possible causes:
damaged MAP hose
low turbo boost
intake manifold or crossover tube hose leaks
damaged MAP sensor
damaged PCM
Inspect MAP sensor hose and manifolds for damage, leaks, restriction and misrouting.

 

Thx chris I'll check that stuff tomorrow in the daylight. I was maybe thinking fuel pressure too might have caused it. I've been running hutch and harpoon for probably 50k and I'm at 150k on my stock pump. It's pushing threw both filters maybe it's on it's way out. Need a fuel pressure gauge

 

Do you have a constant CEL? I accidentally left the connector loose on my MAP sensor when I installed the OBA and had a constant CEL with that Low/No boost detected. Could yours be loose?

 

Checked everything today, all hoses are good. Happened again, same exact scenerio. 38ish mph, and at 1400rpms, this time no codes and neither time CEL. It seems to do it about 5 minutes into driving then it doesnt do it anymore. Im going to check for wiring issues tomorrow. Cant think of anything else that would cause the truck to shut down completely for a half a second? Does anyone know if the icp or map sensors can cause a situation that kills the motor?
The only other things i can think of is fuel or low hpop pressure but im pretty sure the hpop would throw a code.
Are there any economical easy threads for a fuel pressure gauge? thx for any input.

 

If you ignore the boost code, the check the wiring over the drivers valve cover, wiring to the IPR, connector on the CPS, and maybe inside the steering column. Chaffed wires in those locations can cause a stumble.

Of course the CPS has been known to act this way before. Mine didn't throw a CEL until it coughed several times in a row.

 

Thx chris, i always thought that the cps would just quit altogether i didnt know they were intermittent, did yours do that before it finally went? I recently put back in my original black cps because i was getting the wierd idle experience from the grey one.

 

Two days after I bought my truck I was driving down the road and it just shutoff then started right back up did it several times that day .I went to the IH dealer bought a new CPS and replaced it in the parking lot no problems since.

 

When mine started acting up, it had a very slight skip the first time. Slight enough I almost thought I imagined it. Over the next several miles it did it a half dozen more times. A couple of them were severe enough they reminded me of an intake backfire on an old gasser. That threw the CEL on mine. Then it cleared up and acted fine for about 30 miles.

I didn't wait to see what would happen next. When daylight came, I swapped the CPS later that morning, so I don't know how long it would have taken before the truck just shut down.

 

I havent changed out the cps, engine has been to warm this afternoon. I was just at the car wash and the truck was idling while cleaning the windows and it just shut down completely. I checked the fuel bowl and it was full so its not fuel. I will switch it out tomorrow morning and see if it fixes her. Thats funny you say about the lean mixture backfire through the carburetor. In highschool i drove a supped up chevelle with a holley on it with a power valve, vaccum advance secondaries and it would do that when it was cool out, what a pain in the @#$. Holley was great for the track though.lol
It is very similar feeling here when it coughs, im thinking it actually shut down because there was no load and only a few rpms, not enough rpms to cycle through it.
Thanks for your input chris.