Sexy stroker turned into Bucking Bronco...

[Mgardiner1]

I can't tac my jeep over 3K RPM. It immediatly shuts the fuel off. It reminds me like when i had a weak sensor signal from my CPS sensor on my RENIX motor. The sensor has less then 300 miles on it, it was new when i put the engine in (i know it doesn't mean its def good).

I verified all the vacuum lines are fine, and everything is plugged in. It runs fine @ idle and up to 3K i'm reading 14.7 AFR on the meter. As soon as it starts dogging, the AFR goes straight lean (why i say its de-fueling).....

Any idea's???

[yuppiexj]

is the CAM position sensor in the distributor plugged in?

My renix will idle without it, won't rev though.

[Mgardiner1]

I checked it and its plugged all the way in.

[dwg86]

Were you able to get over 3K rpm before?

[Mgardiner1]

oh yeah, i was easily reaching 4700ish without skipping a beat. This started yesterday. I poked around under the hood and found no faults. I got out on the open road with it and it was running just fine. The jeep sat all day, and i took it out tonight and its doing exactly the same thing

[Mgardiner1]

I tried crimping the pins a little tighter in the CPS circuit, put a little dielectric grease on it. Confirmed that fuel pressure is 32 with vacuum line and 40 with out it. i re-verified all the plugs and sensors are tight and fully plugged in. I can rev over 3000 RPM while standing still, but when i get to 3K while driving (very, VERY light throttle) it just immediatly cuts ignition/fuel (i throw ignition in there because the tac drops and bounces up unaturally fast).

So the only thing i can figure the difference between the revving while standing still and driving is engine load... only way the engine should feel a load would be MAP value, right? maybe MAP and TPS... I have to see if i have the MAP sensor off my RENIX harness. I think i threw it away with the harness though...

Any other idea's to check guys?

[Flash]

So it won't rev over 3,000 in N.....? What rpm does it act up if you mash the skinny peddle from a stop?(in Gear)
Flash

[Mgardiner1]

Flash you got it backwards. In gear it will not rev over 3K. In neutral, i can rev sky high

[Mgardiner1]

Came across something interesting. i got out on the road, and accelerated in 3rd gear, the engine would NOT rev over 2800RPM no matter the amount of throttle added. I upshifted to 4th, sped up about 5 MPH and downshifted back to 3rd. The engine was turning just a hair over 3000RPM, and ran FINE up to 4500RPM! I let the revs come down, and it again, would not cross the 2800ish RPM barrier

WTF?!?!

[Flash]

I can't help but thing it's computer related then.....tps wouldn't care if you were under a load or not..........MAP would tho............................
Double check the grounds from the bat, to the block, and the block to the ECM.

Didn't you say your ECM and wiring is from a Renix..........I don't believe they have a rev limiter.......but that almost sounds like what its doing...............You ran this system as a 4.0 before you stroked it...........Is any thing different (wiring and sensor related) this time?

Is it possible that a wire go pinched between the block and tranny??????

Sorry not much help, just some food for thought

EDIT: When you were driving in 3d gear @ 2800, was it popping and back firing , popping thru the tail pipe or intake? Or just running out of power.......like you had lifted up on the gas peddle?


Flash

[Mgardiner1]

no i had renix engine in before my stroker. i'm running a 91 HO harness, ECU, and engine. Flash, i've put 300 miles on it without this symptom, and driving over 3K rpm often!

Its not a backfire, it doesn't pop through either exhaust or intake, its like the ignition cuts off, or the fuel is instantly stopped. It doesn't stall, it keep running after the RPM's drop down. i don't know if its a bad ECU or what. The only 2 things that are relavent to actual engine RPM is CPS.... So i'm wondering if the CPS sensor is failing.... Its only 2 months old, i have a 1 year replacement from Autozone i might take up on unless someone else chimes in with some idea's

[John]

I have ran into that cut out on my ride, was a bad ground. SOB to find. Wouldn't say it is your problem, but it was mine. Intermittent, and when it happened it forced me to drive slower than my grandma.
John

[Mgardiner1]

I'll definitly verify my grounding points tonight as now 2 people have suggested. I'm pretty confident they are ok, but i'll absolutely double check.

Load doesn't seem to matter. If i bring the RPM's up slow enough, i can find the dead spot at exactly 2800 RPMs while in neutral. I might grab the vid came so you guys can hear/see what i'm talking about. Of course if its a simple matter of bad grounds, then i won't waste your time.

Anybody have any experience with bad cam position sensors? What do they usually do when they fail? just quit cold turkey?

[Mgardiner1]

LADIES AND GENTLMEN!!

I have FINALLY found the correct lighting fixture to read DTC from the ECU.... I got a code 13, 33, and 35.

The only reference of code 13 i could find was a pnematic MAP sensor fault.

33 is A/C clutch relay (cut from wiring harness)
35 is fan relay circuit (also cut out from harness)

.............................................................................

I just re-ran the engine (BTW it doesn't do it with engine temp under 160F) and recreated the fault.

It returned with code 12, 33, and 35. Code 13 seems to have gone away at this point. so now i'm confused.


When the engine misses, the CEL does not illuminate.

[Mgardiner1]

Anybody else have any suggestions? After recreating the fault, seeing codes come and go, that night on the ride home, it did not have the 2.8K flat spot.... I hadn't changed anything on the vehicle since the last run when it was acting up.

I've verified grounds, had the cap off the dizzy, and played with some more sensor plugs.

I stopped by autozone today and picked up a new MAP sensor (as i was noticing the AFR's were not as stable as when i first installed my AFR meter), as it is one of the only OEM sensors (other then cam position sensor) left of the vehicle.

Also, i still have not attempted to install my PSC1, not until i get everything ironed out