LST2

I have a mysterious problem with my car bogging which has been getting progressively worse over the last two weeks. At first it just happened at idle every once and a while I would get a rich blip with a quick hesitation and drop in RPM but it would then come back up to normal idle. The idle has gotten worse day by day to the point that it erratically hesitates and bogs down rich every few seconds, then it will go away for a few minutes and come back, sometimes the car stalls and dies at idle. The last two days it has been really back where I would get bucking under load and the AFR is swinging all over the place. I changed my plugs yesterday and they were fouled out black. It seems like some sort of electrical problem b/c the bogging does not have a steady frequency.

I was datalogging the sensors and the only one that looked strange is the injector duration jumps up when it is bogging down. It is hard to say if the injector duration is increasing from a drop in vacuum or if the duration is causing the bog. I tend to think the injectors are causing it as I get the same swing in AFR when cruising and at a steady vacuum.

Today I notice my wideband giving me problems with the heater not heating up. I am wondering if I have a charging/alternator/battery issue and if that could cause the injector pulse to swing this much.

Also, I noticed that my upper radiator hose was quite swollen yesturday after the engine warmed up. I let the car cool down for about 3hrs and opened the radiator cap and a lot of air pressure came out. Headgasket going/gone?


Any ideas?

Update: It is definately an ignition problem and it is getting worse by the hour. I could barely make it home today. It is happening all the time now. It is almost like I am hitting a sporadic rev limiter. It will rev up start to miss then the revs will go down, even when I keep my foot on the gas. It may be my cap/rotor, the contacts don't look good, lots of green powder looking coating on it. Would this make since? I am thinking less and less of a ground, electronic connection issue due to the progressive nature of the problem...

Modified by LST2 at 8:22 AM 6/26/2008


Modified by LST2 at 11:14 AM 6/26/2008

94delslo

Try cleaning out your IACV (idle air control valve) with brake cleaner and see if that clears up your idle/bucking problem.

LST2

I have my IACV disabled in Crome (for about a year now). Also, it is a problem at both idle and durring load.

wantboost

iTrader: (2)

could just be the heat
if i remember right crome doesnt do iat correction

Sr420Det

fuel pump maybe

LST2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sr420Det &raquo;</TD></TR><TR><TD CLASS="quote">fuel pump maybe </TD></TR></TABLE>

Could be, but the problem has been so progressively worse but still erratic. I would think a fuel pump problem would be more consistent.

I replaced the rotor yesterday but that did not fix the problem. In fact, I was getting such a bad misfire that I could not drive the car. I pulled the plugs and they were pitch black, even on the porcelain. This was probably due to me driving it under heavy misfire when I was driving to the shop to pick up the rotor. I had just put in new plugs the day before. So, the new rotor may have solved the original problems, just my plugs were so fouled that I still had the misfire. I am going to put on a new cap, new plugs (this time stock plugs instead of the 8 step heat range I was using). Clean up the intake with some carb cleaner and sea foam and see if that solves it.

The strangest symptom that I have is that it would misfire then completely drop the RPMs while I was still on the throttle. I have my MSD box inside the car and I can hear it working even as the RPMs drop.

I'll have a better idea tommorow when I put the new cap on but I am still open to suggestions. I am almost to the point of moving on to a new car. These ignition/electrical problems are sooooo frustrating.

Mr. Anderson

I was gonna say check TP or Crank sensor...but you said you datalogged sensors... Bad wiring on O2 sensor/map sensor?
I used to have an MSD 6BTM...went through several rotors and caps; switch back to stock ignition and no problem.

Go ahead and do a compression test too, if you are able to. gl

LST2

It was a bad TPS