Map sensor issues after chains replaced
This thing originally had a bunch of timing codes stored months ago and when I didnt have time to do chains it went to another shop. So now its back with its new chains and these codes. Noticed you can feel a slight misfire under a light load. They are not sure if this code was here before I never recorded them bc it was just a quick code pull and thats as far as it went last time.
First thing I checked is the cam/crank and to my eyes its good compared to my known good wondering if someone could double check in case I'm wrong. Odd thing at one point my intake vac was down to 13 and ever since then its been 18-20. Plus now and then I get a strange clatter (comes and goes) out of the engine I'm guessing front head phaser area but hard to tell. Def not the High PSI Pump thats got its own noise. This thing is a disaster
Ive also scoped the 5v ref at the map and signal back to PCM and snapped throttle. My reference seems to stay 5v
Any chance of getting an in cylinder PSI waveform?
I have an RC test saved with an vac transducer on intake but I do not have a WPS for in cylinder
I would chase the; "My reference seems to stay 5v with key on but with engine running its at about 7v". Considering all the work that was just done, this sounds like a man-made problem to me.
Yeah I was wondering about that i thought 5v ref was just that and didn’t change with Charging system on
Exactly. 5V reference should never change from 5V (give or take a few mV either way and the accuracy of the meter.)
definatly look at the 7V everything will be off
In your scope capture with car running only seeing 5 v
Your right I looked again and I must have been looking at the other channels scale. Bc it is actually 5v. So ignore my 7v I said above, sorry guys my mistake.
So this car is fixed. I was able to get a known good cam crank ref and verified timing was on. I tested vac at the map port and booster port to be sure they matched and didnt have some carbon or something blocking the MAPs sample. Load tested wiring to pcm checked pin fit. Replaced PCM and car is fixed codes gone and misfire is to