First time I looked at this the A/C compressor clutch wasn't engaging. Long story short: the high side pressure switch on the back of the compressor was unplugged. Noted that the engine was shaking (like it was misfiring) as I was watching them add refrigerant.
The next day I get the call asking me to look at why the van wouldn't accelerate was misfiring etc...
They had replaced the engine prior, the old one had head gasket problems as I was told. I was also told they compression tested the engine and all the numbers were roughly equal though they couldn't find the numbers they had written down. The intake gaskets are new and plugs and wires are new.
Thinking that the exhaust may have been plugged they disconnected both banks after the manifold, it still won't accelerate. They also tried with the MAF unplugged as well, more of the same.
Pulled whatever codes they had in the computer.
P0102
P0171
P0174
P0175
This makes sense with the exhaust and MAF being unplugged. Though the P0175 may need to be looked at further once they hook the exhaust system back up.
Cleared the codes and let it idle while looking at misfire monitors.
On start up cylinders 1 & 8 showed around 80 misfire counts each. Then the misfire cycles stop for no apparent reason... At least this gives me a place to start.
A capture of engine PIDS on a hot start. Engine MAP is high at idle, suggesting low engine vacuum.
I didn't have a vacuum gauge or transducer with me (I want a WPS500...) so I asked if they had one. Of course they couldn't find one, so I'll leave that for later.
After a few seconds of idling The check engine light comes on with a P0200 Injector Control Fault.
I decided to focus on cylinder #1 as it was the easiest to access and I didn't have anything in the way of hand tools.
This is a capture of the bank 1 ignition and injectors at idle.
Trace 1 (Yellow) is the number one coil trigger.
Trace 2 (Green) is the number one injector trigger.
Trace 4 (Red) is the amperage reading taken at the ENG1 fuse. This powers all the bank 1 injectors and coils.
This doesn't look right...
So I suspect that the engine has multiple issues.
Low engine vacuum according to the MAP sensor reading. Maybe a restricted MAP sensor port? Maybe, but I doubt it the range is too good on the PID capture. Bad MAP sensor? Another maybe. Leaking Intake? I'm pretty sure it is. There was a hissing sound but I couldn't nail down the source. I asked them to smoke test it when the engine was cold and get back to me. Valve timing? Another maybe. The P0175 may be related.
The P0200 code. Honestly I need more time with this one, why would the injector be firing so early? The timing looks off too. I think the harness connections may not be in the right spot. Or there's something wrong with the harness.
Ideas? Comments? I'll be taking another look at it tomorrow probably.
