Very heavy ROMP

DEEZUZ · Aug 26, 2020

Excursion. Pcm had 8 volts for vref and 8 volts for module supply. Installed new pcm. Vref now 5 and module volt is battery. Great.

It still romps. 11% to 33% constantly. All other 5v sensors are great.

New ipr new icp sensor new pigtails. Tried cam sensor tried idm. Nothing. It just romps and then if you hold it at part or wot and let it idle down it dies. Fires right back up.

co04cobra · Aug 26, 2020

Is it a oem hpop or reman of some sort?

psduser1 · Aug 26, 2020

What oil? Miles since oil change?
Sounds silly, but it really might be that simple, I've fought that myself on my ex.

DEEZUZ · Aug 26, 2020

Looks oem.

I did top off with 4 quarts today. I was Gunna change oil in the AM but I am running super short on time and needed some more suggestions. Thanks.

fastersteve · Aug 27, 2020

Have you checked the alternator? Should be 14+ V running. I've seen bizarre behavior with low voltage. Seems like alts only last a few years on mine.

tomlin · Aug 27, 2020

I second the alternator suggestion. Even with it charging at 14v it can be defective. Alternators produce 3 phase electricity. It is rectified to DC through diodes. If a diode fails, you start to get more of the AC waveform. The electronics don't care for AC and it will cause all kinds of weird issues. A good shop with a good scope or scan tool can look for AC ripple.

ghohouston · Aug 27, 2020

I had a crazy ass issue that I chased forever. Truck would buck real bad, kind of felt like a miss, sometimes at idle and while driving Ended up being the female pins in the cps pigtail had spread out due to the wire harness clip not being present.

ghohouston · Aug 27, 2020

I found the issue by wiggling the cps harness with the engine idling.

co04cobra · Aug 27, 2020

Adding 4qts of oil would lean me towards injector orings or injectors themselves. Any back history previous repairs? Did you confirm the hpop is not aftermarket?

DEEZUZ · Aug 27, 2020

Changed oil. It legit idles 10x better. Ipr% only romps from 11-16% but still dies on decel. Will check on pump tomorrow.

All voltages are great, did not check for ac leakage though