schrade

Yates - synthetic oil might smell like plastic when cookin' - some plastics are derived from petroleum. Do you use synthetic?

You could have an unsecured harness cookin' too. Get a utility glove on, and after the motor has been fully warmed up, wipe the glove real hard at the low back corner of the V/C, and see if you pull out a plumb on yer thumb [OIL ]

cwyates4

I am running regular castrol 10w-40, no synthetic here. I will try that test though.

zeitgeist57

225 and purring like a kitten. I'll go for a test drive. Nice night...full moon...10:57pm

BTW, I have no friggin clue what I'm doing. Just following orders, Schrade!

schrade

Get a mirror at the plug, and see if you see this:
http://forums.corvetteforum.com/show...7&postcount=38

My 6 plug was clean. This is 8 plug. ???

schrade

Be ready to turn on the heat, since you got the fan fuse out. You'll get H77 and H78 for fan circuit fault primary and secondary - Not a problem. Watch the heat...

zeitgeist57

HOLY SHIZZY!!! Went out at 11:01,,,coolant at 255!!!

H77, H78 codes? No H41 though...

Going for that drive now...cool off the engine...

zeitgeist57

LOL...just saw your post...

schrade

Fan doesn't come on til 228 on my '94.

I'm tryin' to see a relationship between the fan comin' on and the ICC fault gettin' tripped H42 (ground) for you, and H41 (open) for me.

I did the test once. Fan fuse out, and NO H41, even tho' the temp got to 232 on mine.

This is the most concrete lead I got yet - means it is an electrical problem, NOT a heat problem...

You're goin' on a drive here, and usin' headlights. That bothers me, cause I'm leanin' towards an amp draw causin' this ICC fault.

schrade

No H42 either? I'd probably not do a ride with the fan fuse out there zeitz...

cwyates4

So, when y'all say there aren't any codes coming up, I assume the "stutter" is also gone?

What a weird problem!

schrade

Weird? This is killin' me. I been on this problem since Father's day. I finally got a concrete clue, and somebody else too with the same problem, and he's tryin' to detonate his motor before I get confirmation.

zeitgeist57

11:18pm

Welp...I went tearin' off with the heater running at 247deg.

OAT (outside air temp) was 73 degrees...it got back down to 225-230 in a hurry...turned off heater.

Poked around my neighborhood in the moonlight. Drove around the golf course. Goosed the throttle a bit...no hard driving, just a couple of jackrabbit sprints from 25-40mph and then coast back down in gear...don't want to wake the neighbors...or COPS!

NO CODES!!!! NO POPPING!!! (Well, a little at one point when I got above 4000rpms...) but still NO CODES!!!!!!
EDIT:...still H77, H78, but NOOOOOOOO H41, H42!!!!!!

Riddle me this, Schrade...wtf to do now???

I sincerely appreciate your help! Just by pulling ONE 5a FUSE, I've managed (in a limited test run) to eliminate the H41, H42 codes and bring the engine back to fighting health. I may keep that fuse out for tomorrows highway commute to see what happens...I'll pull over if the temp rises above 235-240 and put the fuse back in...

cwyates4

What about wiring up a switch in the car so you can manually operate the fans, so you can have them on without having the fuse in?

schrade

I would NOT hit the road with the fuse out!!! Even with the heat on high, I don't think you can keep it safely cool at a stop light in daytime.

schrade

What to do now? You askin' me? I'm still tryin' to fish my way thru the FSM. And it doesn't even mention the fan relationship; that was my idea.

So it worked for me, and yours too. Your turn to come up with somethin' now... I'm thinkin' so hard on this all both brain cells need butter cause they're toast.

Still thinkin'...

zeitgeist57

Understood. Sorry...got zealous there since pulling the fan fuse temporarily stopped the problem...

Maybe I COOKED out the problem? Engine got pretty warm!

zeitgeist57

Minor setback...engine was running, and I put the 5a *29* fuse back in. I could hear the engine momentarily take a load, like the fan turning on, and drove off with temp around 220.

As soon as I gave it gas, POP POP POP in upper RPMs, back off...CEL light comes on... H42.

Pull over, reset codes, PULL FUSE for *29*. Drive to intersection, let engine creep up to 210, 212, 215...bump...engine lumps in idle, CEL comes on.

Drive away from intersection...BUMP-BAH-BAH-BUMP BUMP BUMP BAH BUMP all the way home.

H41, H42, plus H77 and H78 for good measure since I pulled the fuse.

Something's fishy, and methinks it's the PCM...I kno NOTHING tho...

Schrade...I'll look for your posts, but I'm going to shower and get ready for bed. 11:57pm...I'll check one more time in a half-hour. If no response, cool...but I'm going to bed.

schrade

Figure anything out Zeitz? I'm clueless...

zeitgeist57

I wish I had access to a GOOD PCM to swap and drive around for a day...

Going for that shower now...

schrade

I don't think we can get over on the motor puttin' that fuse in and out while runnin'. And stoppin' a hot motor to put the fuse in ain't gonna' fool the computer either...

All I'm seein' is the amp draw of the fan kickin' in that causes the ICC fault. That's on the PCM (faulty), or maybe the voltage regulator internal to the alternator. But the draw is ONLY 5 AMPS!!! NOT ENOUGH TO CAUSE PROBLEMS, UNLESS IT'S ON THE SAME CIRCUIT.

AND THE ONLY THING IN COMMON, IS THE IGNITION SWITCH CIRCUIT #210 TO FUSE PANEL.

Even then each fuse 29, and 33 have no relation until the individual fan circuits, and ICC circuits, get BACK TO THE PCM!!!

Where's jfb? Isn't he an electrical engineer or some kinda electric hack?