1985 Grand National will not start.

[Big Dawg]

Hey everyone, longtime. Hope everyone is staying safe out there. I got the GN rolling and have submitted my paperwork to see if I can get some Collector Plates for Insurance here in Beautiful British Columbia.

I have done a few more things to the car, original 87 wheels, and Black Grill. I have collected all the parts needed to do the injector and ECM swap as well as TT chip from Eric.

I have a small issue with the car now, I took off my turbo and replaced it with rebuilt stock 85 turbo I got my hands on from Calgary. Changed out the PCV and grommet ( after dropping into the intake, and fishing it out with scope). I changed out all the vaccum.lines and o-rings as well.

Now when I go to start it, its revving at like 2200-2500 rpm, and only falls to 900 - 1000 rpm when nine reverse and drive. The second its in neutral or park it jumps up again. Can I adjust the small screw on the throttle body that faces up? Also my turbo boost gauge lights up 5 orange lines and nothing more on dash. Which vaccum line controls the boost meter on the dash?

Thanks for or all your help guys.

[Steve Wood]

Have you searched for a large vacuum leak?  PCV not connected?  I don't know anything about the hot airs but it sounds like something is open and allowing a lot of air to come in

[Big Dawg]

I will double check in the morning, I replaced the PCV and grommet and used clamps on both ends of the vaccum line.  Thanks...will let you know what I find.

[Steve Wood]

Just seems like something like a large leak would cause.  Does a hot air have an IAC and is plugged in?

[Big Dawg]

Just seems like something like a large leak would cause.  Does a hot air have an IAC and is plugged in?

Hi Steve, yes it has a IAC And a TPS sensor. I removed them from the old setup and swapped them over to the rebuilt setup.  So I put Corbin clamps and a couple heavy duty clamps where needed on all the vaccum hoses. I also decided to measure how far the idle screw measured vs the one that came with the rebuilt turbo and it was about 1.5 mm off of the screw on the one I pulled off the car, I adjusted it Counter clock wise about 2 turns until it was almost the same as the original and it fired up at about 900 rpms and no codes of any type were thrown. I took it for another drive and the boost gauge works as it should now. I just have to play with adjustable arm to get the boost just right.

After removing the turbo and reinstalling it with next to no issues, I'm thinking I'm going to upgrade the ECM, TT chip, injectors and get the scanmaster and Maf all installed pretty quick here. With my rebuilt turbo I was also given a 3 inch elbow housing and 3 inch downpipe as well. One day I will get it setup with the 3 inch exhaust.


I must say being the GN is my first Turbo car, its been very educational.

Thanks for all your help.

[nocooler]

If you moved over the IAC/TPS did you set them correctly?

[Big Dawg]

If you moved over the IAC/TPS did you set them correctly?

I am presuming i did as I never played with TPS calibration, the IAC sensor was just plug and play. From what I read on all the forums in regards to the adjustment of the idle screw is if you adjust the idle screw than you must recalibrate the TPS. The measurements from the bottom of the housing of the idle screw to the top of the actual screw was 27.4mm, the measurement on the rebuilt setup was 26.6mm, I adjust the screw identical to what the screw on the old throttle Jbody housing was set to, the screw adjusts the throttle body blade.

I am going to take it for a drive when it cools down outside and see how everything goes. I hope to get the scanmaster setup soon, than I will be able to pull the numbers off of that.

Thanks Am

[nocooler]

You can use a voltmeter and paper clips to check the tps voltage. The IAC needs to be within certain parameters as well. All the 86/87 info applies here. If you took off the turbo and throttle body did you reset the TV cable for the transmission? 

[Steve Wood]

take your volt meter and see what the tps is reading with the engine off and the Ignition ON.  I think it should be close to 0.45 v similar to the later cars.

[Big Dawg]

You can use a voltmeter and paper clips to check the tps voltage. The IAC needs to be within certain parameters as well. All the 86/87 info applies here. If you took off the turbo and throttle body did you reset the TV cable for the transmission?

I have never done this before, is there a thread or video that shows how to do this? I have voltmeter handy.

I just unclipped the TV cable along with the other 2 that were on the bracket. The lengths and placements did not change between the 2 setups.

[Big Dawg]

take your volt meter and see what the tps is reading with the engine off and the Ignition ON.  I think it should be close to 0.45 v similar to the later cars.

I will do this as soon as I figure out how to do this.

[Steve Wood]

meter on volts, ground probe on a ground, probe each of the three terminals.  One will be a ground and you will get 0, one will be about 5v, and one should be about 0.45 if I am right.  They are in a different order than an IC car so you will just have to probe

[Big Dawg]

meter on volts, ground probe on a ground, probe each of the three terminals.  One will be a ground and you will get 0, one will be about 5v, and one should be about 0.45 if I am right.  They are in a different order than an IC car so you will just have to probe

Steve, When you say probe each of the three terminals, you mean  the pigtail end or leave it plugged into the sensor, and probe from the top of each wire with a paper clip? With the ignition on , but not started correct?

[Big Dawg]

Okay, I figured out what you meant.

It was 0 on ground, 5V, and .42. I turned the screw and now am at .45....with the RPMs at about 950- 1000 now.

Does this look correct?

 

[Steve Wood]

yeah,, it really should not have made any difference as the window is pretty wide.  Have you tried disconnecting the orange battery wire assuming it has one? Disconnect it for 15 seconds or so to reset the ecm