I have been trying to figure out why my 88 coupe bucks under heave load, and get way too hot when the temp is above 80 degrees. I have been replacing old sensors, plugs, wires, fuel filter, and coil pack. When the temp is below 80 degrees the car acts fine, but when above 80 degrees the car gets really hot and stalls out. Also the wiring to the computer, and the computer itself, we're blazing hot. I found out that there was no TB gasket, so that was fixed, but it still hasn't fixed the issue. I burped the cooling system so there aren't any air pockets. Also she doesn't like to sit and idle at all. I got a code 44 and code 35, which made me think of a small vacuum leak, hence the TB gasket. I was thinking it was leaning out the car enough to really heat up the exhuast. The heat shield around the catalytic converter rusted off, but I cant see why that would affect anything. When I am in 5th gear and around 1300 rpms, then step on the gas it bucks like crazy. I got a new injector, plugs, wires, coil pack, crank sensor, pump and fuel filter. Is there any advice anyone can give? I plan on wrapping the exhaust to reduce the heat in the engine bay. Thanks for the help.
------------------ 1984 White Fiero Sport Coupe (Juliet) in restoration https://www.fiero.nl/forum/Forum1/HTML/089093.html 1986 Gold Fiero Sport Coupe (Oria) 1988 Red Fiero Standard Coupe (Bella) in restoration 1990 Black Buick Reatta (Noir) 2002 White Chevy Impala base(Haylie)
May not be the problem but a heat shield over the cat is not a bad idea. They get stupid hot. My old Chevette rusted a hole in the shield and set my carpet on fire on my way home from work. Made for an exciting ride home.
I have been trying to figure out why my 88 coupe bucks under heave load, and get way too hot when the temp is above 80 degrees. I have been replacing old sensors, plugs, wires, fuel filter, and coil pack. When the temp is below 80 degrees the car acts fine, but when above 80 degrees the car gets really hot and stalls out. Also the wiring to the computer, and the computer itself, we're blazing hot. I found out that there was no TB gasket, so that was fixed, but it still hasn't fixed the issue. I burped the cooling system so there aren't any air pockets. Also she doesn't like to sit and idle at all. I got a code 44 and code 35, which made me think of a small vacuum leak, hence the TB gasket. I was thinking it was leaning out the car enough to really heat up the exhuast. The heat shield around the catalytic converter rusted off, but I cant see why that would affect anything. When I am in 5th gear and around 1300 rpms, then step on the gas it bucks like crazy. I got a new injector, plugs, wires, coil pack, crank sensor, pump and fuel filter. Is there any advice anyone can give? I plan on wrapping the exhaust to reduce the heat in the engine bay. Thanks for the help.
EGR valve is stuck open a little? 5th gear and 1300 rpms.... I don't think the 4cyl will like that.
Check plugs (which plugs are you using), wires (make sure they are seated properly.
What does the temp guage read?
As for wrapping exhaust, you are not going to solve any problem. The car should run the same at 100F as it does 30F.
If it doesn't do this at lower air temps, I doubt it is the cat. converter.
Do you get any more codes? What is the idle speed in park, warmed up?
At idle and warmed up she is around 800. All the plugs have a good seat. They are nice and snug and won't pop off with a good tug. The plugs are iridium and carquest wires. I made sure to check them over before I put them in the car. They were great quality, but the car bucked before I replaced them. (Scratching head in confusion) Code 35 and 44 were the only codes I got.
The coolant I would say is about three years old. It was properly mixed and tested to -40.
[This message has been edited by 1984whitesc (edited 08-04-2016).]
I had a similar issue that I resolved after a year of trouble shooting. After changing every single sensor, every ignition component, EGR gasket, hoses etc it was still bucking under load at a certain RPM and when cold. I tried changing the PROM and that did nothing. In the end what fixed my issue was replacing the ECU unit itself with another one. Now my 87 coupe runs as it should.
I would say its usually not engine bay heat that causes a warm stock engine, its usually a water pump problem, radiator problem, thermostat, fan, coolant tubes etc. Any ideas on what condition of those is? Temp gauge work? Know anyone with a "laser" temp reader?
Hi Andrew, the first piece of advice that I have mentioned to you several times is to buy a factory Helm 88 Service manual. Most everything that you need to know is in that book. The manual specifically states what condition parameters flag a code.
The most common symptom involving code 35 and 44 is low fuel pressure. Get a fuel pressure gauge on the car, go drive it, and watch the pressure gauge. The bucking and low idle stalling are direct symptoms of low fuel pressure. Related to fuel pressure and fuel system is vacuum leaks. You need to inspect the hard lines that route from the fuel tank over to the expansion tank for rust holes, especially under the clamps that hold them to the firewall. Check the expansion tank in the right side quarter panel to make sure there is no rust holes and that the rubber hoses are not deteriorated from ethanol based fuel. Another suggestion that gets overlooked is the condition of the solder joints where the filler and overflow tubes enter the fuel tank. I have seen a lot of this issue lately where these tubes are loose and have cracked solder causing a small fuel leak and also a moderate vacuum leak.
Since you have a symptom that is only present at higher ambient temperatures, another common issue with the 4 cylinder is breakdown of the wiring harness that goes directly from the ECM to the injector. Deterioration from oil saturation is not unusual on the old duke. Also, look at the harness wiring to the IAC, as it is subject to the same issues. Good, solid grounds on the engine harness, especially battery cables should be checked to make sure they are clean and that there is no resistance between terminal points.
Have you replaced the PCV Valve ? A sticking valve give the same symptom as a vacuum leak.
Another thing to look at is exhaust leaks before the O2 sensor. Cracked exhaust manifolds are common on the old dukes.
Lastly, there might be a possibility of a partially plugged catalytic converter if you have one on the car.
The most common symptom involving code 35 and 44 is low fuel pressure. Get a fuel pressure gauge on the car, go drive it, and watch the pressure gauge. The bucking and low idle stalling are direct symptoms of low fuel pressure. Related to fuel pressure and fuel system is vacuum leaks. You need to inspect the hard lines that route from the fuel tank over to the expansion tank for rust holes, especially under the clamps that hold them to the firewall. Check the expansion tank in the right side quarter panel to make sure there is no rust holes and that the rubber hoses are not deteriorated from ethanol based fuel. Another suggestion that gets overlooked is the condition of the solder joints where the filler and overflow tubes enter the fuel tank. I have seen a lot of this issue lately where these tubes are loose and have cracked solder causing a small fuel leak and also a moderate vacuum leak.
Since you have a symptom that is only present at higher ambient temperatures, another common issue with the 4 cylinder is breakdown of the wiring harness that goes directly from the ECM to the injector. Deterioration from oil saturation is not unusual on the old duke. Also, look at the harness wiring to the IAC, as it is subject to the same issues. Good, solid grounds on the engine harness, especially battery cables should be checked to make sure they are clean and that there is no resistance between terminal points.
Have you replaced the PCV Valve ? A sticking valve give the same symptom as a vacuum leak.
Another thing to look at is exhaust leaks before the O2 sensor. Cracked exhaust manifolds are common on the old dukes.
Lastly, there might be a possibility of a partially plugged catalytic converter if you have one on the car.
Thanks for the advice. I checked things over and all looks good. I found out that the temperature sensor was faulty. It caused the car to run all over the place with fuel delivery. Since I replaced it with an AC Delco one I havent had it die on me in stop and go traffic. As an added bonus, the cooling fan works agian, and idles very smoothly. Also it no longer high revs when first started. It still bucks when under a load, but only when cold. There is one thing I have been overlooking and that is the battery. Since I have been starting it a lot, and when the alternator died, it has been getting pretty weak. Another interesting qwerk it acts like it runs out of gas, or like the fuel pump stops working, then just dies. I start it again and runs just fine. It does this randomly when sitting at a stop light. I will have to do some research on this one.
[This message has been edited by 1984whitesc (edited 08-08-2016).]
Thanks for the advice. I checked things over and all looks good. I found out that the temperature sensor was faulty. It caused the car to run all over the place with fuel delivery. Since I replaced it with an AC Delco one I havent had it die on me in stop and go traffic. As an added bonus, the cooling fan works agian, and idles very smoothly. Also it no longer high revs when first started. It still bucks when under a load, but only when cold. There is one thing I have been overlooking and that is the battery. Since I have been starting it a lot, and when the alternator died, it has been getting pretty weak. Another interesting qwerk it acts like it runs out of gas, or like the fuel pump stops working, then just dies. I start it again and runs just fine. It does this randomly when sitting at a stop light. I will have to do some research on this one.
These two bolded things seem contradictory. Possibly the same old problem?
It does seem to be a little contradictory, but it hasn't been doing the same thing as before, like the wiring and computer getting really hot. She hasn't back fired and die when sitting at a stop light (after sustained speed of 65 or more), or stop and go traffic moving less than 10 mph, like it got too hot and shut down. The acting like "it ran out of gas" only happened to me twice, but hasn't done it since. She, however, still bucks when cold, but acts fine when warmed up. The fuel pressure is where it should be.
[This message has been edited by 1984whitesc (edited 08-10-2016).]
I would swap out the iridium plugs for standard AC delco. Did you have your ignition module checked? You could have a bad fuel regulator or the hose in the tank is bad (known to happen).
Again... 1300 RPMs in 5th with a 2.5l... I think you are expecting too much
BUT, you have engine codes, so something is wrong.
I went through the same thing (changed a number of sensors; timing chain and gears, fuel injectors, ad infiinitum), and it turned out to be a broken vacuum line. With the age of our cars and the fact that the vacuum lines get brittle over the years, I always have to chime in to check the lines first. It would have saved me $1500 in labor and parts. Good luck! bb
So.. I thnk I figured it out. I replaced the vacuum lines with brand new hard plastic lines (for the the EGR and MAP sensor) and new rubber lines. I also found some questionable rigging from the PO. That didn't change anything sadly. I got to thinking about what Fred Bartemeyer had said earlier, and though maybe its an electrical problem. So, off to Home Depot to get some 6 gauge wire, terminal connectors, and some electrical tape. I removed the old wiring from the alternator plug, the output terminal and the wire leading to the junction block, cut the new wire to the correct length, spliced them, and tightened everything down. I havent had an issue with her bucking any more. Not to mention no more slow sluggish starts. So maybe it was getting just enough voltage, but not enough amps.
[This message has been edited by 1984whitesc (edited 10-16-2016).]
