: New CEL after pulley and T-stat: ideas?



s4ologist
11-14-09, 09:04 PM
My trip to Houston for the 9 inch crank pulley install is covered in my other post, and I am pleased with the results performance wise.

I got back from Houston on Tuesday, and on Friday afternoon, on the way home from work, I noticed the CEL had come on, and the coolant temp gauge was reading a little hotter. After the install, the temp was stable two lines below 220 (180?). Stock it stayed around what presumably indicates 200 degrees F. Ever since the CEL came on, the temp fluctuates between 180 and 200, and I can't hear the radiator fan. The car runs fine.

It sounds to me like either the fan broke, or is disconnected. The stat stays open, so the temp never gets out of control. Big deal? No. Annoying? Heck, yeah. What to do now? I guess I'll end up going to the dealer and have them fix whichever problem it is (no doubt I'll end up paying, since the area has been messed with during the install, and the computer is instructing the fan to come on at a lower threshold now).

Do the cooling fans tend to fail more with a cooler t-stat, given their increased duty cycle? Still, three days after the install seems a bit premature.

Any other thoughts?

aceofblitz
11-14-09, 09:37 PM
The issue would be clearer if you had a diagnostic tool which can read out the trouble code. My friend had got a CEL and his only mods are the Hennessey CAI and Corsas; issue was from the CAI apparently so he reverted back to the stock intake. But that might have been a one of a kind issue.. probably not with yours. You will never know until you check the code i guess.

musclesbmf
11-14-09, 09:38 PM
t-stat doesn't dictate the temp that the fans come on, that's in the ECU. Did you get a tune with the install? (I hope so to keep the A/F ratio safe.)
What are the temps in San Antonio these days? From what I understand, if the car doesn't reach a certain temp in a predetermined set of time, you can throw a CEL. When I installed my 160 t-stat, Jesse (Wait4me) sent me an updated tune that would take of this problem. Perhaps, if you did get a tune that the tuner missed this parameter. If you didn't get the car tuned, there is your problem, and I would call Jesse immediatley and get his handheld.

Just my $0.02,
Mark

Tony407
11-14-09, 09:53 PM
t-stat doesn't dictate the temp that the fans come on, that's in the ECU. Did you get a tune with the install? (I hope so to keep the A/F ratio safe.)
What are the temps in San Antonio these days? From what I understand, if the car doesn't reach a certain temp in a predetermined set of time, you can throw a CEL. When I installed my 160 t-stat, Jesse (Wait4me) sent me an updated tune that would take of this problem. Perhaps, if you did get a tune that the tuner missed this parameter. If you didn't get the car tuned, there is your problem, and I would call Jesse immediatley and get his handheld.

Just my $0.02,
Mark

Yeah, this sounds about right.

The thermostat will keep the engine running cooler so theoretically the cooling fan should not come on as much since it's running at a lower temperature. At least that's my common-sense layman's opinion. On the other side of that is the fact that my cooling fan comes on within a few seconds after starting my car, so go figure!!

Tony

Titaniumseeker
11-14-09, 09:53 PM
Installation of the 160 t-stat without the tune will definitely get you a CEL. I would contact Jesse (Wait4me) for the tune to resolve this issue.

s4ologist
11-14-09, 10:27 PM
I went to Hennessey twice. The first time, five months ago, I had the intake and headers and tune. The CEL issue was resolved (had to turn off the rear O2 sensors).

This time, all I did was the t-stat and the crank pulley. No CEL for three days, then the CEL came on. At first, the temps seemed stable at 180. Now, the temps vary a bit, and I don't hear the fan any more. They said they changed the fan thresholds (lowered them, I presume) to get the fans to come on earlier. So they did tweak the tune this time as well.

Naturally, I need access to a diagnostic tool, and the most convenient thing will probably be a trip to the dealer.

musclesbmf
11-15-09, 10:21 PM
No dealer.... my recommendation anyways.
Just because they tweaked the fan on off temps doesn't mean they took care of the error I mentioned above. Jesse is very forthcoming with information, so it is worth a call to him to ask what sensor he changed in his tuning to deal with the CEL. Then you can ask Hennessy if they made that adjustment, etc, etc.
My money is on that.
But hey, if you can get a code number, that would be great. That's my I loved the C5 corvette's.... you could read the codes and clear them right on the DIC. Why GM took that away with the newer cars is beyond me.

Mark