So my V6 is having some strange issues and I may have found the culprit but I want to double check.
First of all, the engine is cammed and bored. When you are trying to get it to start moving from stop, you have to give it a tiny amount of gas, otherwise the revs drop like a brick and you get a lot of backfiring. It also has a very erratic idle and has died on me in the past. I can't tell you what rpms it fluctuates between because the tach is all off (probably because its cammed and bored). Once I'm in second gear or so, the car runs just fine.
Also, when I was looking around today I found this line and a matching hole in the back of the engine. I figured that might be the source of the problem but I don't know for sure. After tons of googling I still have no idea what this line does or what its called. My theory is that its a vacuum line, which would explain a whole lot.
Picture of the line next to the hole:
It is located behind the intake, around the blue circle. You can't really see it in this image but its here for reference.
Is there some sort of plug or sensor that I'm missing that goes in there, or should I just shove the line back in?
I put in Rodney's EGR tube. The previous owner had indeed blocked off the EGR. I'm still having issues but it idles a little better. Last night when I was driving it, it died on me as I was coming to a stop. It was pretty hard to get it started again. It would start, and then immediately die if I didn't give it gas.
I think my next steps are to check out the EGR itself and make sure that there isn't another vacuum issue somewhere else in the car.
It lead me to finding out that when the previous owner installed the "cold" air intake, he disconnected this vacuum line.
Now my question is: Would it be kosher to run a vacuum line from there to this existing hole in the "cold" air intake? Nothing was there before, so it would make sense to me.
I just wanted to double check with you all before I accidentally do something stupid since this is still new to me.
I've put in the new line connecting everything and it still acts the same. Nothing I do seems to help this issue. I'm getting pretty frustrated with this.
I have no idea where the MAT is. I'm not entirely sure that it has one. It does have an EGR solenoid.
I do not understand how camming and boring an engine would affect timing. The cam shaft still rotates, as per usual. Ditto for the distributor and rotor.
The timing could be off.
The tach filter could be bad. You should disconnect it to test.
You should change your intake back to stock, with the MAT sensor.
Once you have tried those things, post back with your results.
[This message has been edited by tshark (edited 08-23-2019).]
Now my question is: Would it be kosher to run a vacuum line from there to this existing hole in the "cold" air intake? Nothing was there before, so it would make sense to me.
Find the MAT (Manifold Air Temperature) sensor and stick it in that hole. It and it's connector should be in the front left corner where the original air cleaner was. Follow the harness running under the decklid hinge.
I checked the coil. It was reading more or less correct resistance in the terminals. I also replaced the spark plugs since I thought that might be it. I'm really running out of options here. Nothing seems to be working. Nothing at all.
Its now doing this thing where if I let it sit for a while, it'll start up and then immediately die again. The amount of time it stays alive is shorter and shorter until after about 3-4 times, it won't start at all.
EDIT: I also pulled off the fuel filter and checked that. Clean fuel from both ends, no issues there.
[This message has been edited by Addition1291 (edited 08-24-2019).]
I'm heavily considering throwing in the towel and getting rid of the vehicle. At this point I don't think it will ever run again and if it will, I doubt I will have the money to get there.
Yesterday when I was pulling spark plugs, we tested the spark plug wires too. One of them might be dead and another had higher resistance too. Both were on the same side. I don't know if this would cause the engine to die after starting.
When I was replacing the ICM, I checked the pickup coil resistance and that was perfectly fine.
The fuel pump primes and runs too.
[This message has been edited by Addition1291 (edited 08-25-2019).]
There are some vacuum lines around the MAP. Make sure one has not been disconnected accidentally. Or. unplug the electrical connector on the MAP and see if it runs.
Has this car run well in the past and is now getting worse, or is this a new purchase? And does this car have a cat that could be plugged up? Just btw, my distributor's pick-up coil read fine but was clearly bad. If the plastic on the pick-up or connector to the ICM is breaking down, the pick-up should be replaced IMHO.
You should scrape those pins and the rotor free of rust, but high voltage from an automotive coil can jump through some pretty bad connections and it's not likely that is your problem. Still, high resistance in the distributor cap, spark plugs or their wires can eventually hurt the Fiero's coil. You may have to do some testing here; ignition timing, fuel pressure, TPS, coolant temperature sensor and so forth.
1.) Is there a PDF of that service manual floating around the internet? I have a pdf of the DIY manual and a hard copy of the owner's manual but not that one.
2.) I checked my TPS. It has good ground and good power in. However I can't seem to get anything from the signal wire. I'm not sure what the problem is there.
So today I decided to pull off the IAC. I had read that if the IAC has a lot of carbon buildup, it can cause all sorts of problems.
Sure enough, look at all that carbon buildup. Weirdly enough, the IAC and the port for it had loads of carbon buildup but not the rest of the throttle body.
I'm going to run resistance tests on it and clean it all up and see where that gets me.
You seem to know a lot about this engine, so I apologize if you know all this stuff I am about to write.
Back to square one.....
When you crank the starter and it won't start, does the tachometer move up to 300 or so? If it does not, the primary ignition is not working. That would be the ICM, pickup coil, magnet in the distributor, and a small portion of the ignition coil....and related wires and connectors.
If the tachometer moves, use starting fluid to see if it runs briefly on that. If that works, than you have a fuel delivery problem. If it still does not run, you have a secondary ignition problem. Plugs and wires, as well as dist. Cap and rotor, as well as the ignition coil.
