1993 J30t Runs Rough When Hot

[firestarter810]

1993 J30t
268 000 kms

History
Purchased car, promptly performed timing belt, water pump, tenisioner, pulleys job, laser platinum plugs for tune up . Didn't know about crazy amount of belt tension required for J30 belts at the time, Huge Screeching sounds, multiple attempts at solving issue; finally, while driving, the bolts for the fan sheared off and flung my fan into my rad.

Repaired car, Aftermarket electric fan.
This was five months ago, and the car has driven fine since.

A month ago, I got a tank of gas at a full serve place and he put in regular instead premium, Instead of having it pumped out, I added two bottle octane booster and ran the tank. Car seemed fine, little lagging on power but I baby it. That was two tanks ago.

A week ago, I was driving home, bout half hour of driving, the car would idle fine, but off idle would buck and jerk. Limped it home. found a spit fuel line(thank god no fire) that only leaked under load. Promptly replaced those lines. Car seemed to run fine afterwards.

This past Friday Was driving, same half hour after startup, car bucking and jerking. Limp it home. checked MAF, seemed clean, cleaned it anyways, installed, no difference. Tap tested harness...engine straightened right out. Ordered new MAF for Monday.

Yesterday got the new MAF. Installed. CAR DROVE LIKE A BAT OUT OF HELL!! Total difference in power. OK mebbe not that much lol but a definite difference...

Til this afternoon coming home from work, with tools to pull codes from the 'fixed' car just for s*** and giggles, when at same half hour interval, car does same bucking and jerking.I had to get it towed. I am going to check codes tmw, but there is no CEL. I am leaning towards fuel: filter or pump but I want to get some pressures first. Little difficult when I have to Actually drive it for half hour before it does anything; it idles just fine, no matter how long I let it.

So the complaint is, off idle, any sort of load, car bucks spits pops and does not want to go. Pressing the throttle will force the rpm to rise, but scarily popping and farting while it does. Please help me and this car. I am...getting gunshy in my diagnosis and if I cant find an answer I am probably going to dump this car.

[yodawill2000]

Did you clean and tighten the Maf Connector pins ?
Also I hope you used a Flatbed tow,, Or at least had it lifted on the rear.
If not your transmission will be very upset...

[driverdriver]

Check your codes. Could be your fuel sending unit.

[yodawill2000]

Would that be heat related ??
Heat causes issues with bad electrical connections.
Different metal's expand at a different rate under heat up conditions.
Especially cold solder joints.

[Sinyte]

I been coming here for awhile and finally decided to set up an account, first post . . . But I kinda been having somewhat of the same driveablitiy problem with my J30 . . . I have heard many things that all seem to be the problem . . .
But I'm currently enrolled in a associate degree program for automotive technology and i have came a long way messing with this car the last four years i had it now . . .

But being in school i Have access to Snap-On Modis scanner , i pulled up the Engine data and saw that one of my O2 Sensors was not puting out the reading it was suppose to compare to the other one. its basically was not responding at all.

on the driver side of the engine, i switch both Sensors out tonight with new ones and i havent gotcha a chance to see the differance yet . . .

I been getting bad gas mileage for a while , sometimes 10-13 mpg. . .
when the car sits overnight or the engine is cold and i start it n drive it ,it picks up quicks and responds well,
basically when the car is in open loop it drives well, only sometimes during acceleration the rpm drops while im on the throttle
but once the car is in close loop, and i pull up 2 a redlight or stop its horrible slow off the line , its doesnt respond the same
as when its in open loop. .. .

so im waitin to see the differance now . . .

But if you can get your O2 sensors check and see what they are doing and what reading they are putting out

[driverdriver]

Welcome to Nico sinyte!