Stalling at Idle / Bucking

samishii

Registered User
Hello all. I have a '92 Super Coupe, 5-speed. Stock besides and air tubes.

Recently as I was traveling down the freeway, my 'coupe started to slow down, and I felt a considerable loss of power. I tried to give a little more gas. I seen the Boost gauge move, though I felt no power gain at all. Until I left off the gas all the way, then it bucked forward. I was able to keep the car at 55 until I exited the freeway.

The thing would stall at low RPM, but I was able to keep it alive by keeping the RPM between 1k-1.5k. In gear through at around 30-50 would give me power randomly, and very slight amount of gas given. Again, it would Buck if I let off the gas fast, but not if I slowly let up.

I am currently driving around with out the MAF hooked up, as those synptoms were close to what I experienced before, when I installed the cold-air intake, and a peice of wraping plastic was in the tube blocking the MAF. I figured something got up there (as I have been driving it around with out a filter; stupid stupid me).

No luck. The either tube kit up to the Plenum was empty. The car runs better without the MAF right now, but after the car warms, it will stall at idle. It still bucks a bit when I let off the gas hard, but it runs better then the first night the problem started.

I have no idea what could be the problem. I seen stalling issues around here with the cam position sensor. My buddy doesn't think so. I don't know anything bought cars besides the basics, oil changes, filters, fluids, exc.. So I need some help. (PS my buddy takes a long time to be free to help me, thats why Im asking for advice)
 
You need to install the MAF again and plug it in and run the car a couple times. Without the MAF the car will run like your describing.
 
I just had a similar problem on one of mine. How much vacuum does your gauge show? I had low vacuum at around 8psi instead of the 18psi I normally have at idle. I found a weld crack in my double intercooler causing the problem. You may have a bad leak in your IC tube connections as it's unlilely that a stock IC would be cracked. If your balancer is broken it could do the same thing as was mentioned in the previous post. If so it'll be hard to start as well and eventually won't start or run at all.
 
I just had a similar problem on one of mine. How much vacuum does your gauge show? I had low vacuum at around 8psi instead of the 18psi I normally have at idle. I found a weld crack in my double intercooler causing the problem. You may have a bad leak in your IC tube connections as it's unlilely that a stock IC would be cracked. If your balancer is broken it could do the same thing as was mentioned in the previous post. If so it'll be hard to start as well and eventually won't start or run at all.

18psi at Idle?! ... Im at around the -20 mark at idle... I don't believe I have any serious leaks, except the small leak on the lid. as I make 13 psi at around 5k-5.5k RPM

Last night I put the MAF back on, and no problems...... dumb ~~~ car...
 
That sort of rules out a broken balancer, too. Problem comes and goes? Sounds like a Super Coupe to me. I used the carb cleaner method to find my leak. If it does it again you might try spraying some around to see if it is a vacuum leak. Good luck.
 
Stalling at idle/ bucking (sorry...long)

Just solved the same problem with my 90 XR-7 S/C. It's a high milage car (329km) on the original motor. At around 260km I replaced both O2 sensors, as a PM thing because I felt it was running rich...the tailpipes were sooty, and I was getting some black smoke on kickdown passing. I purchased a new set from CT (Bosch). I put them in and it cleaned it right up.
Things were fine until this summer when my car showed similar symptoms to yours. Sometimes it would run just fine, other times it would run crappy...frequent stalling...dumping fuel at an idle...rough idling....but to drive it down the highway it was always driveable....but would buck sometimes when I would go to resume cruising speed after deceleration.
The car would run better most of the time with the MAF unplugged. I tried a new MAF as the original codes I got were MAF low voltage and Dr/Pass o2 sensors lean too long. The new MAF ran way worse.
I went through some spare parts I had, TPS, IAC, and a few other things...., very frustrating as the car wouldn't do this all the time.
I was running KOEO tests and KOER tests, getting some strange codes.
The constant code was pass side O2 sensor, so I went to CT and bought the one they had in stock. Installing this helped a lot.....no more stalling, but it still idled rough, and smelled very rich at an idle.
Today I went to buy a plate sticker for it and the MTO told me I needed an E-test.....ugh....the notice form didn't mention it, despite having notified me that my Explorer was due. Anyway....wheeled into a garage with it where it failed high on CO at the ASTM2525 test.
Went down to CT, bought another O2, threw it in the drivers side and voila, the car runs amazing now. E-test is scheduled for 2pm tomorrow. Good luck.

BTW the other problem I had a few years ago with low power and bucking under acceleration was caused from a pinched crank sensor cable....it was pinched in between the cylinder head and the aluminum accesory bracket. Once again....it wouldn't do it all the time, just sometimes....but this never revealed any codes at all. What a bear to find this one.
 
Just solved the same problem with my 90 XR-7 S/C. It's a high milage car (329km) on the original motor. At around 260km I replaced both O2 sensors, as a PM thing because I felt it was running rich...the tailpipes were sooty, and I was getting some black smoke on kickdown passing. I purchased a new set from CT (Bosch)........... I put them in and
Went down to CT, bought another O2, threw it in the drivers side and voila, the car runs amazing now. E-test is scheduled for 2pm tomorrow. Good luck.
.

I have converted over to the NGK side
I have found NGK O2 sensors are more reliable than Bosch from sparkplugs.com
And 1.5 extra miles to the gallon, and are in agreement with my WB.
 
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