Suspected throttle issue results in charred rotor and fire

[mckaymotoworks]

Originally written on Pennock's earlier today:
I've noticed since purchase the throttle response in 1st/2nd seems to be all over the place, an intermittent issue. 2nd seems to be the most consistent in producing the slow throttle response. I searched on the board and came across a thread referencing Ogre's write up on the throttle cable stretch, thinking maybe the two are related in some way or both are of issue.

I usually can get about 269 on a tank of gas, today I was at 200 when the car stumbled, died, I was able to get it to crank go another 5 miles to the gas station, the Check Engine light came on for a second when running, then turned off. But, I was within 500 ft of the station on a slight incline and it was stuttering before finally pickin up speed to get to the pump. I filled it up, it only held 8.5 gallons so that indicates there was at least another 1.5 in the tank.

I get on the freeway onramp, slow response, get up to 70 MPH. The car always seems to have good throttle response between 70-80MPH (3rd). I go the next 8 miles to the offramp, which has another slight incline to merge in to traffic, throttle response seems crisp this time. I go another half mile at about 40MPH, slow throttle response.

When I pull into the parking lot, exit the car I smell transmission fluid. Never smelled it until I exited, also the transmission never slipped. It just seems it's not kicking down to the proper RPM to match the throttle position which seems to be causing my above issue.

Now I have this new problem of great concern, the smell of ATF fluid. I checked it last week, the level was good, it did look a bit dark. Had planned to change it, ordered a kit but the kit showed up yesterday missing the filter.



Evening update:

Things almost got real bad and real fast. Flames shot out the back, then the brake pedal went flat to the floor. My guess is the rear caliper seized, blew the line from pressure, fluid ignited. Right before I couldn't get it to barely throttle, the car was vibrating, I smelled what I thought was ATF, must have been brake fluid. The entire rotor is a charred mess in pieces. Hoping no damage to axle or else, won't know till the weekend.

I guess this is the source of my "throttle" issue since this is the left rear on the axle. Essentially the brake caliper was seized on the rotor. 

Friend is coming to tow me home. Thank God I had watered down coolant to douse the fire. Whew

I just received the last bits of my brake parts yesterday minus front hose and calipers. Had planned to replace the whole system this weekend.


So from what I can tell at this point, the cause of my slow throttle response was a seizing caliper, hence what I thought was ATF fluid, though I never saw any on the ground or the undercarriage.

[Fierofool]

Sticking brake pistons is common to the Fiero when it's been sitting for prolonged periods of time.  I was trying to find the link for rebuilding GM rear disk brakes, but can't find it.  Maybe someone else can provide it.  Front brakes are a piece of cake to replace, but the rear have some knit-picky procedures to get them right.  Maybe Roger will hop in.  I think he's the one who has info on the GM disk brake procedures.

Another area that is prone to fire after sitting is the heating and cooling system.  By all means, remove the resistor for the fan motor.  It's located in the front compartment, just to the passenger side of the receiver-dryer.  Critters love to build their nest against it, and when it's energized, it lights up like the element of a light bulb.  With nesting material against it, it's fire in an area you can't get to with an extinguisher.  The resistor has a 2 wire harness plugged into it. 

The general rule of thumb is that the 84-86 Fiero tanks have a 10 gallon capacity.  Only about 8 gallons of that is usable.  Many of us reset our trip odometer at every fillup and don't go beyond 150 miles before refilling.  In any case, due to inaccuracy of old sending units and gauges, use the quarter tank mark as your refill line.  Because the pump is cooled by the fuel around it and passing through it, low fuel can cause failure of an already aged pump.  I ran out of fuel 1 time in a 12 year old Pontiac and cooked the fuel pump. 

After you clean out the critter nests and get your brake issue resolved, evaluate the shifting and throttle response again.  If the problem is still there, it could be the possibility that the fuel pump hose in the tank has rotted and you're picking up air, or that the kick down cable needs adjustment. 

[Roger]

I have the brake info on my computer at home.
I'll try to get time to get it tonight and our resident webpage wizard can post it for all to see.

[Roger]

The files are too large to post them here. We'll see about getting them placed in the Club's Tech Tips section.
I take absolutely no credit for the articles. I just found them after long headaches.
Many thanks to The Ogre and CARQUEST for making the info available.

[Fierofool]

I found one of the articles Roger refers to in our Club Documents section of the home page.  CarQuest Rear Caliper Adjustment Procedures.  We'll need to get permission from The Ogre to post his info, but maybe Roger can email the link or attachment to you. 

[Roger]

Just go here. Great and trustworthy info.

http://home.comcast.net/~fierocave/