so, the $64,000 question is how do I test the ICM?

 

Repeating myself as I always seem to...

The ICM can be tested by most of the larger chain autoparts stores.

 

thanks for the help Swartlkk.

 

No problem! That's what I am here for.

Let us know what you find!

 

ordered a new distributor today.

tested the TPS, it came out just fine, .5V closed, and 4.5V WOT.

cleaned the MAF. looks great now, was covered with some carbon, didnt' change anything.

will test the ICM at the auto parts store tomorrow. is this test a definite good/bad, or is it a value you have to fit inside parameters?

how do you test if the cat is bad? (other than whacking it with a mallet? That didn't help much)

double checked fuel lines, and no visible kinks. still getting high pitched fuel pump sounds. Pressure is ok.

any other tests I should be doing? I'm at my wits end almost.

 

The ICM test should be pass fail. Some stores have different testing apparatus though so I do not know what other tests would include.

Catalytic converters are usually tested for a large decrease in pressure differential across the converter. A pressure gauge is placed in the exhaust pipe ahead of the catalytic converter and readings taken. The gauge is then moved to behind the catalytic converter and, again, readings are taken. The readings from ahead and behind the converter are compared to determine if the converter is overly restricted.

 

I have some new info on the fuel pressure testing. I hooked up the fuel pressure gauge again and drove around until the symptoms came back, here's what I found.

ignition on, engine off: 60-62 psi

ignition off, leakdown only 3 psi.

running at 1000-1200 rpm 52 psi.*(engine has power, and runs fine)

throttle revved up quickly - ~3000 rpm, pressure goes up to 60-62 psi again* (when hot or cold, but only up to about 10 minutes of driving. Which tells me that the fuel pressure reg is working. Let me know if this is wrong)

after about 10 minutes of driving, the fuel pressure slowly goes down to 52 psi and stays there when revving the engine. This is when the bogging/hesitation happens. It stays there when I try to throttle back up.

THEN I put it in neutral, turn the engine off, restart, and presto! I have power again!!! ( this happens in the span of only a few seconds. no time for anything to cool significantly) the pressure is back up to 60-62 psi when using the throttle, and about 52-55 coasting along a flat road.

would a vacuum leak at the fuel pressure regulator cause this? Or could the FPR be bad? OR is the fuel pump bad?

Tried to test the ICM today, the store didn't have the correct fitting for my unit. will check on it again in a few days.

Let me know if you think of anything. thanks again for the time.

Jason

 

It does not sound like a mechanical problem, more electrical...

 

Well, I tested the ICM at the auto store today and it passed just fine.

I have a feeling its the fuel pump. Any suggestions before I order a new one?

 

I just bought a 98 s10 with some issues to say the least. Having similar difficulties, I've been troubleshooting for a few days now. In my case the truck was throwing a code. Don't remember the number but it was low voltage sensor 1 bank 1. I just bought 2 new Oxygen sensors and I'm about to install them, so I'll let you know how that goes. Many other new parts were installed prior to my purchasing the vehicle... fuel pressure regulator, plugs, wires, fuel filter, etc... All the research I have done on the issue has not once indicated that a faulty oxygen sensor may be the cause of this problem. Hence the reason I mention this. Like I said, I'll let you know in a few hours... wish me luck.

*UPDATE*

well after plenty of pb catalyst and a lot of pulling 2 new O2 sensors have been installed in my 98 s10 but alas, same issue. i suppose in the morning i will be disassembling the ignition system. That seems to be the next logical path. also i have yet to mention, it has 218,000 miles on it. Cars don't die, people kill them....