Electrical issue with a 3.4 twist (Page 1/1)
gatorfrey DEC 20, 04:57 PM
Ok,
Yall, have seen a bunch of posts by me lately, and yes, I am all over this 1987 GT that has been neglected for a while.
Here is my latest thing.
The car has a 3.4 engine. As bought, the coolant temp gauge needle is laying inside the gauge face, and someone has put a aftermarket gauge on top of the instrument pod.
While under the dash removing a Viper security system that was making the lights flash every time I start, I saw the grey wire that came out of the aftermarket gauge running behind the carpet to the back.
Later, I am back on the engine, changing out the fan switch to a slightly lower one, when I notice the grey wire coming up the firewall, and to the nearby sensor next to the fan switch.
I assumed whoever did that was avoiding pulling the cluster to fix the factory gauge.
Well, I got impatient on not going to get the correct socket for the fan switch, and used improvised tools. I knew better, you would think. But noooo ! So yea, I bent the neighboring switch next to the fan switch. Sure enough, on the next drive, the aftermarket gauge did not work.
Well, I was going to replace/repair what needed to be done on that temp gauge anyway, to get back to factory. So, I bumped it up to next thing to tinker with.
I located a gauge, and plan on pulling the instrument cluster to replace that. Then I went to the Fiero store website to get a sensor. Looking at the locations, the gauge sender is on the other end of the engine !! The neighboring sender next to the fan switch looks like a cold start injector sensor. Sure enough, there is a plug an inch or so away that is pulled back, and that grey wire uses a simple non factory connector at the top of the sensor.
Externally, the 3.4 looks like a normal 2.8, as far as I can tell, down to the "Fiero" intake and thermostat housing.
So, does the 3.4 use the same cold start sensor? If so, I am ordering both sensors, as the gauge sensor looks a little rough.
Any 3.4 guys out there know?
olejoedad DEC 20, 06:02 PM
As you are running the 3.4 all dressed up like a 2.8, then yes, you should use the cold start injector and switch. Are you running the Fiero ECU?
gatorfrey DEC 20, 07:17 PM
I bought it like that. Yes, it looks like a 2.8.
I also noticed the cold start manifold sensor next to the fan switch is not easy to find to replace.
I have no idea if it has the fiero ecu. I know little about this conversion.
It's a cool car though. I am going to bring it back from a few years of neglect.

[This message has been edited by gatorfrey (edited 12-20-2021).]

Gall757 DEC 24, 04:35 PM
IF your engine looks like a 2.8, then yes you need a cold start sensor. New, they are expensive and hard to find, but very durable, so finding a used one should work fine. It's possible, but unlikely that your PO switched computers.

[This message has been edited by Gall757 (edited 12-24-2021).]

Raydar DEC 25, 10:09 PM
Cold start injector?
I deleted mine when I did my 3.4. I never had any difficulty starting it, but then I live in GA, so the coldest it ever gets here is usually in the low 30s.
I was also running 19# injectors, but I had a bunch of other mods, too. Ran acceptably well on a stock ECM/chip. Well enough even to pass emissions.

Edit - The gauge sender is, indeed, on the opposite end of the engine, underneath the coil.. One wire runs the gauge, the other runs the warning light.
Probably what happened is that the temp gauge kept "pegging" when the engine was started (a common Fiero problem**) and knocked the pointer off of the stem. The pointer can very likely be shoved back on the stem. To make the gauge as close as possible to "accurate", turn the key on, with the engine dead cold. Don't start the engine. Stick the pointer back on the stem, with the pointer lined up with the bottom line on the temp gauge. (Obviously you'll have to take your cluster apart to do this.)

The two sensors on the intake manifold are for the cooling fan (single wire connector) and the cold start injector (rectangular two wire connector). If one of the sensors was running a gauge, it was a replacement sensor. Both of those sensors are just switches.
Maybe a bit redundant, but I hope that helps a bit.

** The fix for the pegging temp gauge is well documented, here and elsewhere, but I can't lay eyes on it, just now.
It involves switching wires at the sender (IIRC) and behind the cluster.

[This message has been edited by Raydar (edited 12-25-2021).]