Fiero issues (Page 1/2)
Storm2077 JAN 19, 08:09 PM
Hello all, first post here. Long time reader. My second Fiero.

A 1984 Fiero SE L4

So I bought this car from a friend & it worked fabulously for about 2 months. A lifter went kaput. So I replaced it, of course the gasket didn't seal properly so I had to do it again. After this I had the issue of a blown head gasket. So I took it all apart & had the head surfaced & rebuilt. I put it all back together with issues with the thermostat housing sealing to the block, took a special made rubber gasket. I replaced the temperature sending gauge & coolant sensor as well.

So here is where the fun begins. The dash has the temperature light lit up. When the car warms up the idle will go from ~1000, drop to 300-400 for a few seconds & then bounce back up to ~1000 for a few seconds & then repeat. When driving it seems to not have full power & in 3rd & 4th & feels like it stutters when the pedal is depressed. So if I unplugged the coolant sensor the car would idle properly but at ~2000. While driving it still had the above issues. Oh & the heat for the car doesn't get warm so I'll assume the heater core might be an issue, but that wouldn't cause the above issues. Please correct me if I'm wrong. Also sounds like a slight exhaust leak, haven't found where yet.

I'm running out of ideas & I miss driving my Fiero. Could it be a ECM? Heater Core? Bad Sensors? Did I put the block on wrong (rods, rockers) , Exhaust leak.

If I can hopefully get some input from the master on this forum before I have to take it to a garage. Thank you all in advance & I'll try to keep up with replying as I'll be on vacation starting Monday.

First Fiero. 1986 Fiero GT V6 automatic
Second Fiero. 1985 Fiero SE V6 (parts car)
Third Fiero. 1983 Fiero SE L4 Manual
Patrick JAN 19, 08:16 PM

Welcome. First thing I would check is that you have a functioning 195° thermostat. Sounds to me like its either stuck open... or missing.

Best thermostat for this application is a Stant SuperStat 45819
Storm2077 JAN 19, 08:20 PM
It is a 195° Thermostat, & is functioning per the boiling water on the stove test.

As for the car not quite sure as my car is "overheated" at start & driving in the 10° Ohio weather.
Storm2077 JAN 19, 08:23 PM
Also the temperature gauge is maxed to the right after approximately 2 minutes of start.
Patrick JAN 19, 08:36 PM

It's possible you have an air pocket. For advice on how to "burp" the Fiero cooling system, This is how I do it.
Storm2077 JAN 19, 08:42 PM
Would this cause the idle issue &/or the lack of power?
I figure it could cause the no heat issue.

[This message has been edited by Storm2077 (edited 01-19-2020).]

Patrick JAN 19, 08:53 PM

I was offering some simple initial steps to take.

There appears to be a problem with lack of heat from the heater core, despite what your temperature gauge is telling you. Since the temp gauge is highly inaccurate at best, getting a scan tool on there to find the actual temperature being communicated to the ECM is critical to figuring things out.
Storm2077 JAN 19, 08:58 PM
Gotcha, I'll have to get a reader then.

I'm think of flushing the whole system as well. Prior to the car blowing the head gasket, the heater worked fine, the car didn't overheat, no issues of lack of power.
Storm2077 JAN 19, 09:00 PM
I also I'm assuming the lack of power is from the ECM maybe going into limp mode if the ECM thinks the car is overheating causing lack of power. Maybe also the idle is from this as well.
Patrick JAN 19, 09:10 PM

With the work you've done, make sure all grounds are clean and have been re-attached. Lack of proper grounding can cause all sorts of weird engine/electrical issues.