Huge hesitation, mechanically inclined. Please help

[Brian Wilson]

Pulled the fuse as a test first thing this morning. Everything seems great. Not sure how long it will last. I'm going to run it a few days and then put the fuse back and see if the problem returns.

 

[Brian Wilson]

Could my use of valvoline synthetic dot 3- dot 4 brake fluid have caused this? Someone said it could. Not sure if it is accurate but I'm a all synthetic fluid guy. Never had a problem before.

 

[Rocket Man]

I'm not sure but that sounds like you should definitely look into it further. Im strict about using recommended brake fluid. Too many horror stories about ruined brake components from using wrong fluids or failure to get all the old fluid out and ending up with a mixture.

 

[Chip18]

The Dot 4 "should be fine" but I'll let someone else answer that one. Take a closer look at the harnesses on all the wheels for the "ABS" sensor wires?? I'm "assuming" these have them??

On my 951 the "ABS" would go off and the dashboard would light up like a X-MAS tree whenever I hit a bump most disconcerting?? You have to shut the car off and restart to rest it ... it was other wise fine so ...whatever.

While working on other issues ... I noticed the wheel harness for the ABS system?? I also noticed that both sides did not look the same?? It's a 89 944 Turbo S and "somewhere" along the line some A-Hole decided ... to hack up the harness on the driver side??? The grounds were missing on that side?? Don't know if these vehicles have a similar ABS Harness setup ... just a thought.

But ... another idea ....

https://www.google.com/search?q=inf...=chrome..69i57j69i61&sourceid=chrome&ie=UTF-8

Maybe one of the brakes ... is dragging??? One of those is a way to find out ... I should get one myself.

 

[Chip18]

I'm not sure but that sounds like you should definitely look into it further. Im strict about using recommended brake fluid. Too many horror stories about ruined brake components from using wrong fluids or failure to get all the old fluid out and ending up with a mixture.

Yeah ... I'll go with this. PT Cruiser ATF 4 ... only!

 

[Brian Wilson]

Is a mixture a bad thing? I always try to flush out completely but it's hard with brakes by yourself

 

[LADenali]

If you've done the following:

1. Booster: You'd experience longer braking times, plus this is only in effect when you brake.
2. Master Cylinder: When replacing, did you bleed on the bench prior to install? Sometimes air gets trapped and is not properly bled off.
3. Front Calipers: They seem to be reacting fine if your experiencing pressure.

I'd say the proportioning valve is the culprit. I tried looking up the GM parts list but cant seem to locate it. Not sure if its folded into the ABS system.

 

[Chip18]

Is a mixture a bad thing? I always try to flush out completely but it's hard with brakes by yourself

Just to this ... :

https://www.motiveproducts.com/products/0118-bleeder-race-pack

Freaking "Porsche" (944's) are a bleeding nightmare to bleed without one!!

 

[Chip18]

If you've done the following:

1. Booster: You'd experience longer braking times, plus this is only in effect when you brake.
2. Master Cylinder: When replacing, did you bleed on the bench prior to install? Sometimes air gets trapped and is not properly bled off.
3. Front Calipers: They seem to be reacting fine if your experiencing pressure.

I'd say the proportioning valve is the culprit. I tried looking up the GM parts list but cant seem to locate it. Not sure if its folded into the ABS system.

Aww "portioning Valve!!" It's gotta be in there somewhere??? Hey did a search ... it looks like it's not buried at all.:

https://www.google.com/search?q=gmc...5qvPAhWDRyYKHbOtAyIQ_AUICSgC&biw=1093&bih=541

But the infrared thing to read brake temps to see if there is a problem with an individual wheel, would be a good idea before screwing around with that system!!

 

[Brian Wilson]

It's definitely both front brakes. And pulling the abs fuse helped for about a day. Problem came back. Going to see if there is a proportion valve between the abs assembly and the front calipers.