So I have an 86 turbo, manual trans. Bought it a little while ago and so far replaced the ecu valve cover gaskets. Car ran perfectly fine before I fixed leaky valve cover gaskets and put it back together. Idles and revs fine when sitting in the driveway, though does smell rich and has slight hazy white smoke that you can barely see, not sure if normal or not? Running 87 octane btw, not sure what the opinion is on that, so far I've read that people do and do not like running 87. I've adjusted the TPS with a multimeter and tested for vacuum leaks which I couldn't seem to find any though I plan on replacing the lines anyways since theyre all old and original. I have also replaced the plugs on the harness going to the injectors.

Well I decided to take the car on a little test drive down my neighborhood and see how it drove, since it would run perfectly fine sitting in the driveway other than the fuel smell coming from the exhaust.

At first, everything was going well. Car seem to drive smooth and didn't seem to hiccup at all... until I go downhill with it. Going down hill I notice the car isn't revving really or it is hesitating whenever I try to give it gas. After going down hill it just seems to sputter and slow down no matter how much gas I try to give it until it dies. I guess since the car is warmed up it starts burning oil on the driver side again, from what I think is the still dried up oil on the exhaust that leaked on there when the valve cover was still leaking.

So, I restart the car and it seems to hesitate a bit, but I am able to get it back into gear and it drives relatively normal back up the hill until I am able to park it back in my driveway.

Any ideas on what this could mean? The car doesn't make any sort of weird noises in the engine bay nor have any leaks that I can see. Does have a slight whirring noise almost coming from maybe the valve covers? Maybe a little below? Will attach a link to a video of it running to see if anyone might be able to tell if there is any weird noises. I ordered a new FPR as the vacuum line coming from it smelled a bit like gas.

Tried running codes but wasn't sure if I was doing it right? I have a refurbished ecu since I couldn't find any for sale for my model. I don't know if it reads differently than an oem ecu as it would just blink both led's at the same time followed by the green led a certain amount of times. I still need to see if the spark plugs need replacing too as well as the fuel filter, but everything seemed to run fine until I replaced the ecu and the took the plenum and lines off and put it back together. I'm trying to think on what could've changed since putting everything back together, maybe the ecu is actually reading sensors correctly now and some sensors are bad? I don't know what would make it just start to lose power like that though...

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Also sorry if this is not posted in the correct section!

 

If the air flow meter is going bad, the car will idle fine but won't rev up past approx 2K

 

At first I was it would drive just fine and rev up past 2k, but didn’t act up until I started going downhill. Maybe I’m just out of fuel?? My digital dash doesn’t work right now since it doesn’t have a power supply and I can’t read my fuel level.

 

Yeah, if there is a question on how much fuel is in the car that would be a reasonable first step. Especially the only going down hill part.

A car designed for premium should really be run on premium. Small effect on performance and fuel mileage.

 

Ah thanks! I've been trying to read around and find a definite answer but only really found a mix of people saying that it was fine to run 87 and others saying their car ran like crap with it. I don't mind paying for premium, but wanted to make sure I should be running it!

 

Well, the detonation sensor will retard the ignition timing on regular. That makes the relatively small difference in performance/mileage.

If filling it up doesn't work you should be able to pull the codes from the ecu. The factory service manual shows how to pull and how to read the flashing codes. I think you can find the FSM online for free.

 

The Z31 turbo is not designed for premium. 87 octane is what is recommended. I have driven my 85T over 300,000 miles and see no difference between 87 and 93 octane. If the timing is set correctly, using 93 octane is a waste of money.

 

If the timing is set correctly, and there is no detonation, the octane is irrelevant

 

Sorry, I have the Z32 and ASSuMEd the Z31 would be the same for fuel requirements and detonation sensor response.

 

Ah so I shouldn't be running premium in a z31? I thought as it seemed to run perfectly fine on it before. Though it seems like my problem has to do with low fuel, as like I said, it only started acting up when I started going downhill. I'm sure that the gas that was in it was bad too as it sat for several months while I was waiting for parts.

Before I continue work on it I am waiting on a new fusible link as one of them was burnt out and corroded but just twisted back together. I'm assuming this happened because one of the previous owners put on the battery backwards one time so they tried a quick fix or something. I also have a new FPR as after I had the car running I could smell a slight fuel smell in the vacuum line coming from the top of it and was thinking that is why I have the rich exhaust smell. Would that be the possible cause of it? Would a faulty FPR also cause my exhaust to be covered in a layer of black soot? My exhaust has looked like that since I got the car, and the fuel pump was previously hard wired on a constant source of power before I had replaced the ecu and was able to reconnect it to the harness.

 

I also need to do other tune up related things such as replacing the fuel filter and new plugs and wires. I had the oil, coolant, and transmission fluids changed not too long ago though

 

Put in the new power supply and confirmed I was dead out of gas lol. Only things I really need to do now is find out the rich smell from the exhaust, and spark plugs and rotors.