2.5 tbi bucking and jerking

[bluneon]

i can duplicate the problem @ wot.

in 3rd or 4th gear on wot, rpm's rising to just under 2K. the car jerks and bucks like there's no tomorrow.

the only way to stop it is to punch the clutch in and rev the motor up above 2K and slip it in. i say WOT because this is seems to be the easiest way to duplicate the problem every time. it doesn't happen all the time under normal driving, but it does happen.

i got stranded in the middle of an intersection this morning on my way to work. the car started bucking and jerking, i punched the clutch and the car stalled out. coasted to the red light at the intersection. got it started back up and went on green. nope stalled out again. thought i had to get it towed, but after a few traffic light cycles i was able to get the car started. limped it into work the rest of the way having to turn off to let the drivers from piling up behind me if/when it does die on me again.

i've replaced the HEP with a new one and didn't fix it.

94 dodge shadow 2.5L tbi.
thanks.

[94sundance]

any codes?

[moparfreak3]

Fuel pressure-fuel pump or fuel filter
TPS sensor

[bluneon]

just scanned the car just now.

drb shows injector control circuit #1 trouble code. 1 ignition cycle ago.

[94sundance]

also could be bad o2 sensor causing it to run rich and buck maybe

[moparfreak3]

O2 sensor wouldn't cause it to buck, run rich maybe, but buck no.

[bluneon]

i cleared the code. test drove it and the code never came back on. test drove it a bunch of times and the code still doesn't pop up. even after duplicating the problem a bunch of times.

i threw in a spare injector i had laying around, still did it.

threw the fuel pressure guage on it, test drove it, pressure holds steady @ 40psi while it's doing it. it doesn't seem to be bucking and jerking, more so just cutting out.

tps sounds promising.

i've gone through most of the steps in the diag manual and it's stating that the egr is bad. so that's suspect.

[Twisted Noodle]

Not sure if it is the same problem I was having. I originally thought since I had changed the plugs and gaped them to .030 instead of .035. I re-gaped and the problem went away for a little while.
What the problem ended up being was the alternator was on it's way out.

My car was cutting out at around 3000 Rpms. After the new alternator, it is like driving a new car.

[bluneon]

i am still running on the original alternator. i know because the car has been in my family since new. i so happen to have a spare alternator laying around, so i'll toss that in when i get the chance.

i got further in my 'no codes' diag procedures to where the book said i had to replace the egr valve. i wouldn't know if the egr was the problem or not so i bought a new one and tossed it in. nope. 90 bucks that i didn't need to spend...lol.

[Twisted Noodle]

Try the Alt.

My new problem now is... I thought everything was great, The car idled better, had more power.. even the windows went up fast with out me "helping" them up. For some reason I just happend to put a Voltmeter on it... 18.4 volts!! So I guess next on my list is a voltage regulator... these things happen.. I guess

[IROCNOROLL]

Quote:

Originally Posted by Twisted Noodle Try the Alt. My new problem now is... I thought everything was great, The car idled better, had more power.. even the windows went up fast with out me "helping" them up. For some reason I just happend to put a Voltmeter on it... 18.4 volts!! So I guess next on my list is a voltage regulator... these things happen.. I guess

Voltage reg is part of the power module on the older cars, and SMEC / SBEC on the newer cars. Unless someone has done the external stand alone VR mod.

[IROCNOROLL]

Quote:

Originally Posted by bluneon just scanned the car just now. drb shows injector control circuit #1 trouble code. 1 ignition cycle ago.

Does the code come back with the testing you have done. The control circuit is just that, the circuit. This encompasses the harness to the injector, the injector itself, and the SBEC which houses the circuit and driver controlling the injector timing and on time. A failure of the driver itself will cause the symptoms you describe, as will a harness or connector issue on the circuit.

Now, having said that, common failures of the coil, plug/coil wire flash over (leaking insulation allows spark to seek ground outside the cylinder), carbon tracking in the cap, Simple to test. And issues like temperature can affect the windings on a failing coil.

A MAP sensor that is off calibration but not totally failed (open / short) enough to set a code could set the condition, as could a loose or poor (cracked) vacuum hose to the MAP.

Also try a wiggle test on the engine harnesses. Start with the various multi-plugs behind the battery and with the engine running, pull and twist the harnesses one at a time to see if there is any reaction in the idle. Connector corrosion and heat related expansion in these connectors, including the main connectors to the SBEC are relatively common, and will sometimes present the condition your having. Also all the fusible links connect from here too. What were they thinking wrapping the computer around the battery anyways. Corrosion looking for a place to go. HTH

[bluneon]

the code does not come back whatsoever. i tested the alternator and it shows that my battery and charging system are fine.

my coil died on me, i had a new one laying around, popped that in, started right up. while i was at it, iput in a new cap, rotor and wires. my plugs are fairly new, i replaced them this summer.

test drove, no codes. although when i duplicate the problem the car seems to be running better than before, BUT it still does the whole cutting out thing. sometimes it cuts out @ around 2K rpms when i'm @ wot. sometimes it bucks and jerks. sometimes when it cuts out, especially in 4th gear it feels like the motor wants to start back up again.

the MAP is original.
the car has around 187,000 miles on it.

[corey simon]

Try replacing the fuel filter if ya didn't already my 93 daytona 2.5 was doing the same thing changed the filter and it runs fine

[jim34]

Id suspect the tps