Maf or TPs?

[micker]

Hi, got a 1997 and it showing codes for TPS & MAF. Cleared code and tps came back. Put in new one and it still Idle rough and run strange. Sometimes throttle stick high and have to restart. Have to put in nutral at stoplights. It runs OK on hwy but don't shift right all the time. Sounds like it breathing hard too. TPS & Maf codes came back.Anybody got any ideas? Please help !
Mick
P.S.
I think the codes were reading -out of operating range

[maxwedge]

Disconnect maf see how it runs for testing only. Try and post exact codes also.

[mustangmike351c]

use a volt meter to make sure its reading voltage from idle to w.o.t. key on engine off. should read around .5 at idle to just under 5 volts wide open. if your readings are off you might have the tps installed wrong

[LeSabre97mint]

Micker

Is the high idle problem befor or after you put in a new TPS?

On my 97 I had run ability problems because of a bad ground on the passenger side by the battery. There are 4-6 wires going to this ground stud. This may or may not be your problem. The computer ground is included in this ground. It wound't hurt just to pull the nut, clean the wires, and put a light coating of grease or other anti crosive stuff on.

I was told by a GM mechanic that this ground has cause many problems on these cars.

Regards

Dan

[micker]

I did unplug MAF and it got a little worse. also chanded TPS and got no change. Took it to a " specialist" on sensor stuff and he's confident that it's the MAF. Will get one today and let you know.
Thanks for the replies!

[Blue Bowtie]

FWIW, any leakage of the intake ductwork between the MAF and TB will send the MAf signal "out of range". Before you condemn the MAF, make sure the connections are good and the intake ducts are sealed. That includes the CCV supply tube which is usually connected to the ductwork downstream of the MAF.

[micker]

Hi, put the new maf in and it runs better but still not right. The light stayed on and it still has trouble in the idle and also does't want to shift down in to pass mode until you shiftdown by hand the first time.Idles weak at stoplight. The code is still 102 -like the current is to low or something.That came back right after startup before I moved.It seems to go Hwy speed just fine.Never had this stuff before the engine was swapped. It threw a rod a few months ago.

Any ideas about this low voltage tps ? THANKS!

[BNaylor]

Originally Posted by micker

Hi, put the new maf in and it runs better but still not right. The light stayed on and it still has trouble in the idle and also does't want to shift down in to pass mode until you shiftdown by hand the first time.Idles weak at stoplight. The code is still 102 -like the current is to low or something.That came back right after startup before I moved.It seems to go Hwy speed just fine.Never had this stuff before the engine was swapped. It threw a rod a few months ago.

Any ideas about this low voltage tps ? THANKS!

DTC P0102 has nothing to do with low voltage or low current. It means MAF Sensor Circuit Low Input (Frequency). The PCM looks for a frequency related signal from 1500 Hz to 11,500 Hz depending on airflow. It has detected your MAF for whatever reason is putting out less than 1500 Hz. However, it is consistent with a bad MAF sensor. Check the intake and look for any obstruction. Also, remove and clean the throttle body screen at the TB input. You can use throttle body or spray carb cleaner. Clean the throttle body bore if you have not already done that. Do not clean the MAF sensor with these type chemicals. Make sure MAF sensor is properly sealed and tight where it mounts to the top of the throttle body and the two Torx screws are tight.

For the TPS check the 5 volt PCM reference voltage at the electrical connector. Do the same for the MAF sensor. The TPS output back to the PCM will measure .4 volts dc at idle and 4.0 volts dc at WOT. Voltage in between as you move the accelerator should be progressive and linear with no flat spots. For MAF output I use an oscillocsope.

BTW - When you install a replacement sensor like MAF make sure the PCM is reset to clear the original DTC. To qualify my MAF sensor statement and based on my experiences with SII 3800s, 99% of time the MAF is bad when a P0102 DTC is set but there is always that 1% where it is another problem.

On the engine swap what year did it come out of?

[Blue Bowtie]

I've been informed that the MAF is integral with teh TB on this particular year/model, so disregard the ductwork comment for this engine, but still look for leaks after the TB and in the CCV system.

[micker]

Hi, quess I wrote # wrong on code but it read tps low something. Checked tps with meter and it showed 5 total volts just like you said, and it move smoothly when throttle is moved.Unhooked batt completely for 20 minutes and still checklight on and rough idle. The rest of the systems seem good. So I got a bad wire or pcm {ecm}? Think I might have to let IT rest for awhile. I spend another wad for nothing might have to move to Wyoming if ya get my drift.
Thanks for Everything