Poindexter10thae

iTrader: (2)

I'll just go ahead and post all of the symtoms right here. After the car runs for about 20 mins(either idling or driving) the engine will buck violently, in all gears, does not do this while the clutch is in(of course) but when reving the engine in neutral you can watch the RPMS and it still does it. When it bucks the RPMS do not drop but hold steady and the car just jerks violently and will not accelerate no matter how much gas I give it. I have already checked the entire driveline(clutch components, tranny, U-joints and rear-end) they are all good. The problem is either the fuel or ignition systems. I have checked the fuel pressure(both inline and deadhead pressure) it is good, checked the pressure regulator and it is good as well. I checked the codes and did not have any, so I went to the troubleshooter in my snap-on scanner and it mentions an article about a bad ground, looked up the article and checked the ground, I have good ground(the strap that goes from the block to the firewall and provides ground to the ECU). I know there has been some talk of ECU grounding, if you want to check this you need to measure the resistance of terminal 3a and 2R on the ECM, there should be 0 ohms resistance for each(just thought id throw that in). So far the only things I have found to be bad are
1. solenoid resistor
2.Spark plugs are Extremely fouled

Now here is the list of components that I have checked so far and have found to be good, no problems with this stuff
1. BAC valve
2. clutch switch
3. all 4 injectors
4. A/f meter
5. driveline(clutch components,tranny, rear-end)
6.plug wires(2 weeks old)
7. chassis and ECU ground
8. fuel pump
9 fuel pressure regulator
10. water thermo sensor
11. intake air temp sensor

I am stumped. I am replacing the spark plugs as soon as I am through typing, but I dont think that will help. This is my daily driver and I depend on this car, I cant drive my carb'd N/A anymore because of blown water and oil seals on the
intermediate housings. Please help me out

Erik

hey man, i just sent you a PM...do you have a turbo or n/a. so for the first 20 minutes your car is fine? but after that is when it starts bucking?

HAILERS

May I suggest that you go open your hood and disconnect the TPS plug, get back in and drive the car around the block. Did ole buck go away? Hopefully he did. If he did write back. If not, just pretend this post did not happen and ignore it. You do have the symptoms of a bad tps, but again, it could be something else. Small car with the potential for a lot of different problems.

Poindexter10thae

iTrader: (2)

I drove it with the TPS disconnected for about 40 yards and it bucked worse than it ever has. I could not rev the engine past 2500 RPM in any gear(including neutral).

Keith

Hi. Coupla' questions. You mentioned that the solenoid resistor was bad. Have you replaced it? Is the new one good? More importantly, have you recently replaced injectors? If you have, did you order low impedance injector replacements? You mentioned that you have a scan tool. Did you scan while you were driving the car and the failure was occuring, or at idle? I ask this because the 86-88 ECU's do NOT store codes, they will flash a code when the failure is occuring, and as soon as the failure disappears, so does the code. When you checked the A/F meter, did you check it by checking voltage at the second pin from the back with it connected? When you check this, it should vary smoothly, without any dropouts, from < 1V with the plate closed to almost 5V with the plate pushed wide open, with no dropouts in between. You should do this check as close to the failure occurance as possible. You might want to disconnect the O2 sensor when the failure occurs just to eliminate this as a possibility. When the failure is occuring, you might want to stick a timing light on and see if you are missing flashes on the leading ignition. Also, you should check if the timing is steady or shifting between 1000-2000 rpm (You might need to add some extra marks to the flywheel pulley to see this). I hope this helps to isolate your problem. Have a good day!

Irv, Keith's dad

Poindexter10thae

iTrader: (2)

Hey Irv! please help me! here we go, in order
1. injectors were no replaced but were checked with snap-on multimeter(m504) and the Snap-Vantage ; Tested optimally
2.It isnt the solenoid resistor(my mistake) It is the variable resistor that is mounted on the strut tower behind the A/F meter(adjusts idle mixture)
3. Codes were checked with the snap-on scan tool with key on engine off, while in idle, and while driving with the problem persisting; Absolutely 0 codes
4. The A/F meter was checked with the procedure in the factory service manual with a multimeter, AND was also checked with the snap-on vantage meter at idle AND while driving with the problem occuring.
Test went fine and the A/F meter is good.
5. The timing light was my first step in Troubleshooting this, just didnt think anyone else would think of it! I am getting steady spark even when the problem happens and I have also checked both Coils and ignitors.

HAILERS

Irv, father of little Keith, please tell BigWoogie not to write back until he has a simple, easy to fix problem (humor).

Poindexter10thae

iTrader: (2)

INTERESTING REVELATION: Ok so I am out driving last night, redlining, pushing it hard, just counting the seconds before it starts bucking. So it starts bucking insanely hard and so I decide to fill up with gas(seeing as how I was on nearly E) I fill the tank, start the car, and begin to drive off. No bucking, first thing that comes to my mind is "WHAT THE F*&%". Then I remember the guy that I bought this car from told me he had to replace the fuel pump. Now this guy was white trash(like most 2nd gen owners in austin, sorry,correct me if im wrong, but i dont see any others) now the guy had already put in a cheap reman'd battery and im guessin he went to the local pick'n pull and got himself a hell of a deal on a fuel pump. Some quick notes:
1. the bucking problem has been happening for about a month now, it just got really bad the past 2 weeks. I have put plenty of gas in the car so it wasnt the simple mistake of running out of gas
2. I am thinking that either the fuel pump has some issues or that the in-tank fuel filter is either clogged, disconnected, broken, or some other hillbilly error with it. So basically my theory is that for some reason the gas is not getting to the fuel pump from the tank and especially when low. I will test this further and post results, I am going to test the TPS this weekend(please be the TPS) and keep yall updated.

Please keep the posts coming, I appreciate all the response and I can definitely use the input at this point.

HAILERS

Hey! You asked for more posts, you'll get em. There was a problem about a month ago with several of us having the engine cut off during hard left cornering. Unlike others, I came to the conclusion that it was the filter on the fuel pump. I took mine out and noticed that the fuel was trapped inside the filter element while I held it in mid air(it was coming out of the mesh, but slower than what was reasonable). I took that filter element and soaked it overnite in laquer thinner. Reinstalled it, and now I can run with a gallon or less in the tank, and make really aggressive left hand turns without the motor cutting off until I straighten out. Easy to check out . Just maybe ten screws and two clamps. Other folk say that the removal and replacement of the fuel pump is the way to go on the problem described above. Also some people on that post mentioned that their cutout was with a nearly full tank, quite unlike my car that cut out on hard left turns when the fuel was less than an eighth full. I mean, when I turned left aggressivley, the car flat died, until I straightened out. Well, if nothing else, this will bump you to THE TOP. EDIT....It can not be the tps. You disconnected the tps and still had the problem, said Hailers with certainty.

Poindexter10thae

iTrader: (2)

oh definitely, Since thursday night I have had pulling the fuel pump on my saturday agenda. The only thing is that most of the time it does it when im going straight line acceleration.

Tonights drive:
drove it hard tonight for about 30 miles, with a full tank it does the bucking, it is actually more of a hesitation followed by a single buck, only in second gear and it does it at 4500 RPMs and at 5600 RPMs, then continued to accelerate throughout the rest of the powerband. I do think there is a issue with the fuel pump, thats why i am pulling it for inspection tomorrow.
Note: Tonight was much more different than al other times when the problem arose, it was much worse earlier