I'm having to borrow a computer because my internet is down for a few days. If this has been covered recently, I'm sorry. Just point me to it and I'll go from there.

The car is a 79 Trans Am now with my bone stock 96 LT1/T56 that was in my formula. The PCM has been changed for a 95 PCM and has a stock M6 tune in it. I have changed both the knock sensor and module. I have turned off the normal stuff, CARS, EGR, VATS and adjusted turn on temps for the fans down. The fans are the factory 96 formula fans but I control both through the fan 1 relay signal. I wasn't going to deal with trying to wire those the way the factory did.

Here's what is going on. The car idles at 1600rpm and the fans are commanded to and do turn on shortly after starting the car. The coolant temp according to the scanner is normal and acceptable. Desired idle is 800 rpm. IAC counts stay above 50 the entire time. MAF is flowing 11-12grams/sec. TPS is at 0.7V. There are no vacuum leaks. The idle is smooth just high.

I only cleaned the TB when I had it off the engine. I did not touch the throttle stop screw and have not either. I believe that would be a band aid and not a solution. If it was the solution, IAC counts should be at 0 or close to it I would think. I've verified that the IAC wires are in their correct locations both at the valve and the PCM. I've adjusted the IAC Park vs coolant temp table in Tuner CAT down with no affect to the way it runs.

Any ideas on what is going on? I believe the fans being commanded to turn on early is a clue. I've looked through my book but have not come across anything.

Thanks for the help.

 

Trouble codes cause the fans to come on. Check for codes.

 

Forgot to mention that I don't have any but I have turned most of them off, lol. Wouldn't the scanner still show the code but the SES light would stay off? I could have sworn simply un'x'ing the box made the light not come on but the code was still there.

Would any of the AC stuff cause this? I don't have the AC hooked up and haven't changed any of those parameters.

 

Well, I backed the throttle blades back just to see the response from the engine. There was no response. So I must have an intake leak somewhere. I have no idea where though. The only thing I did with the intake manifold before putting it into the engine into my TA was to delete the EGR stuff on the back and remove a few of the fittings on the side of the manifold that supplied vacuum to emissions or AC stuff. I've blocked everything off and tested for leaks with starting fluid with no response.

I'm still not sure why the fans would turn on early though. Does anyone have a voltage to pressure conversion chart so I can look at my MAF correctly? I'm seeing 0.7~0.8V while idling at 1500~1600 rpm

 

If you mean MAF there is no voltage to verify, the MAF sends a variable frequency determined by the air flow to the PCM. You said pressure conversion, if you meant MAP then there is a voltage to pressure chart. Voltage varies from 0.3V at 0 MAP to 2.2 V at 50 MAP to 4.9V at 100 MAP. Also are you using EVAP, if not did you plug the port in the TB ?

 

Sorry, I did mean MAP but obviously typed MAF. I just wanted to make sure my reading of 0.7~0.8 at 1600rpm was normal.

Yes, I believe all ports on the TB are closed. I'll have time tomorrow to pull some stuff and look at it. I can't run the car though as it's supposed to rain and I can't put the car outside in the rain.

Thanks for the reply.

 

There's a conversion chart showing volts - "Hg - kPa conversions in my ScanMaster writeup, under the MAP heading.

http://www.injuneer.com/ScanMast.html

If you are getting 0.70V that would correspond to 6.5"HG (22kPa). 0.80V would be about 7.1"Hg (24kPa). Both those are lower than I would think would be possible. You would normally see 9.5-10.5"Hg at idle with a stock cam.