Chevrolet :: 1992 - At 60 - 65 MPH Backfires / Lack Of Enough Power To Downshift
Apr 9, 2011
I have a 1992 Chevy C30 Step Van. V-8 with automatic overdrive transmission. When driving in hilly terrain at around 70/75 mph, the van will lose some speed and when it gets to about 60/65 mph it backfires and seems to lack enough power to downshift. I've tried not using the overdrive selection and it does seem to do a little better, but stil backfires some. I've changed rotor and distributor cap and tried higher octane fuel.
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My 1992 Plymouth voyager 3.0 looses power when it gets hot I put a straight pipe thinking it was the catalytic converter and still doing the same thing also it backfires
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All stock 460 in a 1987 1-ton 4x4. The carb has lost it's cookies I think. It (all of the sudden) developed this massive flat spot right after I shift gears and open the throttle. It falls on its face, then catches and slams the whole damn truck.
Also pop-pop-pops really badly when I downshift and occasionally backfires when I shut it off. I'm (barely) smart enough to know that it's getting excess fuel dumped through the engine. I just pulled out both float adjusters, cleaned them, and reset float levels and it made no difference whatsoever.
It's my only vehicle and it's barely drivable.
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Hey I've had this truck since 2009, it's a 2000 silverado 2500 (nonHD) extended cab long bed 4X4 with the cast iron head LQ4 (6.0) and 4L80E trans. It has almost all the options of the day...
I bought it with 77K it now has 138K and has had this problem since the day I got it... When accelerating it intermittently has no power from a stop. It has really high gears (like 3.42 or 3.73) as opposed to our farm truck which is an 05 2500HD which has 4.10's...
What happens is when I take off from stop, it will be a total dog off the line it doesn't matter if the tank is full or empty, truck is hot or cold, part throttle or WOT. Regardless it has no freaking acceleration. That is until you get to just before the shift point then the power comes back and it puts you in the back of your seat just like a 6.0 should. Then the truck shifts into second and has the normal amount of power.
I have had several local mechanics try to fix it, it has been given a tune up plugs wires filters etc. It has had the TB and MAF off and cleaned. Over the years the fuel pump and sending unit replaced etc. Over the years I have replaced the O2 sensors (with ac delco) both cats, IAC TPS crank positioning sensor, EGR and possibly others...
I have put a fuel pressure gauge on it but it never seems to have a problem when you have time to mess with it..
Possible other theories include but are not limited to: Fuel pressure regulator? some intermittent vacuum leak? partially collapsed lifter?
NO CEL, it runs smoothly though lately (last month or two) the idle is all over the place... tends to idle high... It has had a slight knock since I've owned it.. I had a theory that maybe the knock sensors were pulling power, but wouldn't that trigger a CEL?
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I have a 67 chevelle and it runs great but after driving it a while it starts backfiring. I think it is when it gets hot, is this possible and why is it running hot. It is a straight 6. 3 on a tree. Smaller engine like a 250 or something. Original engine and everything. I have had the car since I was 16, now I am 40. Somehow I still don't know how to fix it.
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I searched a lot but did not find these symptoms on my 1992 Aerostar 3.0 2WD with A4LD transmission.
In overdrive, accelerate to down shift, and the transmission goes out of gear. Engine revs as if it was taken out of gear. Manually shift to Drive, and it works fine.
Overdrive works fine if at speed, and works to shift up, but if going slow enough to drop to lower gear, transmission goes out of gear. Manually in drive, works fine.
I may have other symptoms, but this was on the way home from work, and I just parked it. I checked fluid level, and it was fine, still in the cross-hatch area of the stick, light colored oil, no smell.
I will replace the modulator and replace the filter, and see what that will do. If the overdrive works at overdrive speed, I do not see how that could be an overdrive housing failure that I have seen in many posts. I am aware of keeping track of the pin for the modulator.
I also have read that band adjustment is not a good idea. If they are worn that bad, they should be replaced. I don't think it is a band or clutch problem. I think it is a shift control problem. We will start with the modulator and filter and take it from there.
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So my 92 4.0 automatic has always been kind of a slug since we've bought it with 101,000 miles on it. It's been tuned properly and fuel pump, filter, and regulator been replaced. It runs pretty good but when you're going highway speed or even like 45-50 and stomp the gas it doesn't feel as if it's downshifting. The transmission looks like it may have been replaced or maintained, it shifts good, pulls good. Fluid is clear and clean, no leaks, no burning. I see that it has a vacuum modulator valve but don't know where it hooks up to. I can barely see it behind my catalytic converter. It will have to be removed to change it for sure. But I'm trying to see where the vacuum line goes from that modulator valve. I see the valve but I didn't really notice a vacuum hose coming off of it but again my view was obstructed by the catalytic converter. Would it cause hesitation problems if it was bad or not even hooked up?
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I have had a few times when my 2013 Chevy Traverse LT suddenly jumped to a low gear while quickly slowing down, causing the RPMs to jump up to 4-5000 RPMs. It remains in that gear until I am practically stopped. Is this normal?
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I have a 337 running the ATP gt2x kit with revo stg3 and external fuel w/550cc injectors. The car has power in the first three gears until 4200 RPM then it acts like it backfires and then looses all power, but it will drive and boost normal in 4th,5th, and 6th gear. I have basic boost settings running on the revo and cant figure out what the problem is.
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My 2007 mini cooper with low milage (40,000) began making clacking noises, then backfiring, then loosing power. Had intake valves cleaned with walnut shells a few months ago at great expense and just started to click and clack again? Put in fuel injection cleaner and has stopped for now.
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Replaced the clutch on my son's 01 Cavalier 4 cyl. Replaced Clutch as it was slipping, and replaced hydraulic throw out bearing/slave cylinder at same time. New throw out bearing failed after only 500 miles or so, seal broken, started grinding on down shift and coasting (deceleration) followed by leak and no pedal. Replaced with new Slave Cylinder and Throw out bearing, the new one is starting to show same grinding noise on shifting and deceleration. What could cause this? Used the spline alignment tool to adjust the plate on center the right way. Could the pressure plate springs be off center? The flywheel was purple could it be warped and throwing the pressure plate springs off center thereby causing them to rub against the I.D. of the Throw Out Bearing slave cylinder seal?
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2007 F-350 6.0L, Wife phoned and said that the truck backfired a couple of times and there was black smoke from exhaust. When she stopped at idle there is now alot of white smoke but coolant level looks fine. She has about 200 km's to go before she is home pulling a 20 foot horse trailer with 1 horse.
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I have a 2012 Cruze with a manual transmission. I have 43000 miles. When I down shift into 2nd gear I get a whining noise from under the car. I can shift it with no issues and no noise but when down shifting or turning in 2nd gear it whines.
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My issue I'm having - 2002 F350 7.3L has an 8 inch bds lift with 37/13.50 tires. I realize these tires are big but... while driving 100kms/hr or 60 miles per hour and I hit the gas the truck barely wants to move (without pulling a load). Thought maybe a turbo but I have no mechanical skills so here I am!
2nd issue, there's a bullydog chip in that truck when I bought it. he said he always ran it on extreme. I found it puffs way to much black when on extreme and on performance it seems a lot better so that's where I have it?.
3rd issue, the transmission gauge on the dash goes into red when climbing up hills ( I live in the rocky mountains so a lot!) but the bullydog chip says the tranny is only at its hottest 140C? I don't believe that's to hot but I do believe my truck is derating a little while the tranny gauge on the dash is in the red? is there any quick fixes out there for these issues.
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I was driving and my truck started have lack of power, could barely get going on hills, tons of blue smoke (smelled like diesel) real rough idle. I unplugged injectors and found #5 made no difference. I replaced it today and I can't get it to start. It'll get to 2000+ psi 48v ficm, low pressure oil registers, ficm says its in sync. It will crank and blow a lot of black like its half firing or something. It has even crank to, until it tries to fire. From what I've been reading could it be the ficm? That one circuit is fried?
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I have a 2003 with 150k miles. My 6.0 has black smoke and can barely crawl up a hill. Dealership is 30 days out for an appt. Air filter, oil change, alternator, and batteries are new. I removed the EGR valve and cleaned, but the valve seat is not perfect. I can see 20 to 30 mil gap around half of the seat. Is this ok or will that little gap cause this?
Hoses all look good. No alarm lights. I have no diagnostic tool but I can use a meter well. It did have an airbag light but I found the fuse missing and replaced it. The air filter alarm switch fell apart but I bypassed it till I get new part. No alarm lights now.
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While I'm cursing at highway speed everything is fine. But when u punch it it pass someone it's like I actually slow down, same from a red light. I've got a livewire programmer in it and this problem is somewhat new. It just seems to keep getting worse, I was going up a hill on the interstate this morning and at 2800 rpms I was actually slowing down. I'm not sure if the fuel pump is going out or if the transmission is slipping or what.
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Blown fuse causing a lack of power to the OBD port?
I just got my Kiwi2 BT OBD2 adapter and was hoping to start diagnosing my truck, but the adapter won't power on while connected to the truck.
I pulled and visually inspected fuse #12, I also verified power to the cigarette lighter plug and the accessory 12v power outlet.
The adapter powered up with no problem when I connected to a co-worker's Tacoma.
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Long story short, when going up hill or any incline for the matter it feels like it's struggling and lugging, blowing carbon everywhere. It's an automatic so I yeah can downshift sometimes but even turning overdrive off doesn't work in a lot situations. My EGTs are way too high and I'm not about to tow my project car to OKC unless I get this figured out. I live around Salt Lake City so towing can be hard up surrounding passes. Just cruising to park city at 70mph on I80 up a pretty good incline my EGTs were 1,000. Just driving around the city, some hills I see 700-800 when I'm going 35mph.
At stop lights I'm seeing 400 at idle. My probe on the pyro is going bad starting to flutter but even if I fix that I'm still having issues up hills. Boost is good, up-pipes don't appear to be leaking but fuel pressure is a little low @56 and I know it's not the fpr because I just messed with that yesterday, put a new poppet and oring in, I haven't checked the fuel pump yet or dropped the tank either. If it is in fact fuel pressure related, does it make sense for me to see smoke coming out, wouldn't that indicate too much fuel? I'm lost, it's driving unloaded like I'm pulling an anchor.
Regardless of which spring I put in the frx I get 56psi, even with the black one I may see 58psi but even with 58psi it was still lugging it's butt off up hills and making that terrible drone sound like F you down shift me now.
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I have a 2004 f350 with a 03 bullet proofed motor. The truck did not have any power and the turbo wouldn't support until I put a new vgt solenoid in and it ran great for about 3 miles... Stalled doing 65 kinda lacked power while accelerating but got up to speed quick. I pulled over and no start. It is running error code kam on pcm from disconnecting batteries but could this cause the stall and no start? Or should I be looking into icp sensor?
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Having some problems with an e-350 dying when in gear and rough idle. Truck starts up after it dies. Vehicle acts like it is starving for fuel. I have check fuel pressure after fuel pump and getting 55psi. High oil pressure pump with in normal ranges. Cleaned and checked egr and it was in the closed position. Fuel filters have been changed. Injector buzz test ok.
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