Ford - Thunderbird :: 1991 - Intermittent Spike In RPM With A Lurch In The Engine
Oct 22, 2012
I get an intermittent spike in RPM with a lurch in the engine when I'm holding anywhere from 1500-1700 RPM. I say it's intermittent because it might happen three or four times over the span of a few seconds, and then nothing for a minute or two. I don't think it's the transmission because it doesn't happen during shifting, and I can duplicate the problem in D, N, and P. What could be causing the problem?
1991 Ford Thunderbird SC, 3.8L 6 cyl with supercharger, 4 speed automatic transmission172,000 miles
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Engine is a 69 390, fresh rebuild by the PO... Aluminum intake manifold and new Edelbrock 4bbl Drop in Crane ignition.
Runs great... Except when its warm out, or even on cold days when its warmed up after a substantial drive..
AT that point here is what happens: No issue until I shut it off then it diesels badly, THEN.. When I restart it will not idle, dies.. If I keep my foot on the accelerator it will keep running, but not well.. If I let it run for a good while, 5-10 mins, it smooths out... Consistently acts like this .. Again.. Not when the engine is cold, and not on a cold day until it really warms up..
I suspected a vacuum leak? Replaced any suspicious vac tubing.. Cant get to the AT modulator easily, have not checked it yet?? Also suspect the intake manifold??
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It had no spark when I put a spark tester on, a few minutes later it started and runs fine. This has happened several months ago. Is their a way to test the spark control module.
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It could happen once a month or 3 times a day. No pattern and never the first time I start my car for the day. But I will be running errands, park the tiguan, run into a store for 5, 15 or 30 minutes and when I get back in my car and start it up and go, it dies when shifting from 1st to 2nd. I know how to drive stick. This doesn't happen every time. I have called/taken it to the dealer 5 times and they have no clue because it never happens with them and I cannot predict when it will happen again. Also, on occasions, when i start my car, halfway through the day, the engine will idle really rough then the RPM's will spike and the car gives itself gas and my foot is definitely on the brake. These little issues are starting to piss me off, especially since the dealer just shrugs its shoulders.
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I have a 1995 Ford Thunderbird with the 4.6 V8. I have owned it since it was a year old, it now has 70,000 miles on it. A couple years ago it developed a problem while driving. Hard to explain, but seems like it is misfiring or there a fuel restriction somewhere. This shows up when i floor it, the transmission kicks down and the engine struggles to accelerate, you can feel when it clears up, the car shoots forward. It seems like if i smoothly step on the pedal it is better, but not always.
This problem is also noticeable when the revs are low, like just before the transmission shifts down, like when climbing a hill, you can feel a shudder, if i accelerate and the transmission shifts so the revs are higher the problem goes away. Also, shutting off the overdrive so the revs increase works too. It really feels like the engine to me, although it does not go as far as to backfire.
2 years ago i replaced the auto transmission and torque converter with a factory one direct from Ford.To diagnose what i think is an engine problem i have: replaced the fuel filter (wasn't dirty) removed the injectors and had them cleaned and tested (they were fine) checked the fuel pressure (fine) checked the vacuum (fine) removed the exhaust to look for cat blockages (nice and clean) replaced the plugs, wires, and coils checked that the timing was in spec, although i don't think there is a way to adjust it
The car has the early version of OBDII - it does not have any active errors.
The car starts and idles fine, cold or hot, and when it is not acting up, still has excellent power. It does sit inside all winter though.
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I'm working on a 93 thunderbird with a 3.8 in it and no check engine lights are on.The engine races at about 2500 rpm in neutral, I changed out the TPS but the idle still was way too high.
My first thought was a vacuum leak and I did find one hose that was rotted away. I then tested for vacuum leaksby spraying some brake cleaner around the intake and all the lines and fittings, but the engine stayed at a constant rpm.
My next guess is the Throttle Air bypass valve.
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I have a 1979 Ford Thunderbird with a V8 5.0 liter engine. Here's the mysterious problem... the engine turns over when I turn the key but stalls when the key is released. Thinking that the alternator died, I replaced it with a new re-manufactured unit and the car's symptoms stayed the same. Also checked the fuses and the fuel filter and found that plenty of fuel is getting to the carburetor. This issue with the car not starting appeared literally overnight after I attempted to install a new radio. Prior to this the car ran reasonably well – always started easily and ran without a problem. Wondering if there is a possibility that I fried some part of the electrical system when I fussed around with all the wiring under the dash. Someone else had attempted the radio installation previously so the wiring there was already a mess of cuts and re-connections and was hard to sort out.
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I've notice this several times when leaving from work to go home. The first quarter mile I will be starting off nice and easy, the engine is on and then suddenly a lurch of power. Now its not giving me a wipe lash! But I can defiantly feel it and out of the corner of my eye can see my passenger's head move back slightly. So not so subtle either. It will only happen once.
It is not going from battery to gas as I mentioned engine is already on. I am in eco mode the whole time. I am not hitting the gas any harder. And I am not going into the power band all the way right of the bar. I am staying steady in the eco area.
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It acts like it is fuel poor, As if the fuel pump is not pumping. It spins fast on start. Then another try and it starts! No relationship to hot or cold. Fuel OK. Battery strong. I find no corrosion on fuel pump leads.
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I have a 1991 Honda Civic DX and it is doing something I can't explain. Randomly the car will not even try to turn over. The ignition switch will click, the dash lights come on... but not even the slightest peep from the starter motor. If I put the vehicle in fifth gear and roll it, turning the engine over even half a rotation, the engine will fire right up.
It started on a road trip and happened very sparsely, but has since become more common. What used to be 1 out of 20 is now maybe 1 out of 4 chance it doesn't start. Every now and then it will go days without any problems, then seemingly randomly the ignition fails again for spurts. I replaced the distributor cap, plugs, and rotor about 2 months ago. The ignition switch appears to be fine....
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I've been searching for a while now but have not found an exact match to my problem.
So, Yesterday I was pulling a large load home (15K lbs) over flat land/small rolling hills and I experienced a coolant temp spike. And I am trying to figure out what caused it. I was traveling 65 mph about 2k rpm and 20lbs of boost, I was motioning the ECT, EOT, TFT, and Fan Speed via my scanguage and 99% of the time the ECT was in the 209-220 range, once it got up to 220 the fan would come on and the ECT would drop to 209 ish pretty quickly.
However, twice the ECT shot up from 215 ish to 240 within seconds then the dash indicator said check coolant temp then the fan came on and cooled it down to 200 within seconds, I did lose about 1/2 gal of coolant. So today I'm going to get a new degas cap (still OEM original) and continue to monitor the situation.
My EOT ECT delta has been a constant 10-13 degrees for the 3 years i've been monitoring it so i believe my oil cooler is still functions within spec and all my cold soak temps are within a degree or two for various ambient temps (20 -80) so all my sensors should be good.
Also, tonight I'm going to pull the EGR valve and check if there is any coolant in the intake, but if there is not, where should I start looking and what should I start worrying about e.g. head gaskets?
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While driving at any speed my temp gauge and oil pressure gauge spike well above "H" and stay there. The red battery light sometimes flickers too. The Battery gauge is low. I replaced the terminal to then negative battery cable because It was loose. I have also replaces the alternator. I had the battery checked and it was good, it just at 45% charge. That's why I replaced the alternator. After I did that, It seemed to have fixed the issue. But after 3 days, it has come back again. Now this morning on the way to work, driving down the freeway, my speedometer jumped to 85 MPH and there was a squealing like noise coming from the engine. I am not sure if the two are related issues.
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My 2004 ford explorer 4.0 has this issue where the check gauges will come on for 2-3 sec, then the temp gauge will go from normal and peg to hot and as soon as it pegs it drops right back down to normal. I have had the thermostat replaced and have flushed the radiator. I am at a loss here....
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A warm startup on my 2007 Explorer causes an RPM spike and subsequent stall (half of the time) on the way back down. I've tried a fuel additive, Ford ran codes with no problems...
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My v10 when air is running every few months all of a sudden spike to hot and got to reduce power, i turn off air and in 2 minutes it goes to normal, i can start air back again and not have any more issues to a few months later it will do same thing again, it will not does gradual climb and fall it will spike all of a sudden, turn off air and it will go back to normal in 2 minutes...
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ok this is my first diesel ever its an 01 7.3 powerstroke 250 4x4 . with 4 inch exhaust and used to have a programmer on it but it is supposedly back to stock. so I can be driving say in 4th gear and just hit the on button for cruise control without cruise being on and my boost will go from like 15 to 30lbs pretty quickly.... why on earth would it do this the previous owner was an old man who pulled horse trailers and had no clue why either ???
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Dad's 2000 F150 5.4 ltr will start intermittently, when it does fire it runs fine, but right after start up all the dash gauges "spike" to the max levels for a sec and then go back down to normal....
Put the Cen-Tec 98614 code reader on and it continues to say "Link error" and I can't communicate to the interface. P.S., I confirmed the Code reader is good by pulling a 420 O2 sensor code from my Toyota in just a few seconds....
I can hear the fuel pump kick in so I doubt that is the culprit. Because of the gauge spike at start up (every time) this problem screams grounding problem, but I don't know where to start. Could it be a faulty relay?
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Have a 91 Aerostar that won't start. Has fuel pressure, pulse to fuel injectors, strong spark, strong compression, etc.
Thinking that the spark may be coming at the wrong time I tried a spare ignition module that I keep. No luck. Since my distributor had a lifetime warranty I got another one, again, thinking spark was coming at wrong time. Nothing. Engine won't even pop.
I am going to drop the front pipe in the unlikely even that the new converter is plugged or, somewhat more likely, the muffler, but I am leaning toward a computer at this point.. Still don't understand since it is getting spark and gas why engine won't even pop.
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In the past month or so I've noticed some weird behavior out of my car. 2006 Mini Cooper 130K miles on it (still going strong!!) Automatic.
Scenario 1 - Driving in D accelerating at a normal pace (read, not gunning it) the RPM's spike rapidly from 3K to 4K and the car almost sounds like it's redlining. Once it hits 59-60 MPH it drops back down to 3K RPM and the rest of the acceleration is normal.
Scenario 2 - Cruising on the highway at about 70+. Normally start taking the foot off the gas to slow down with traffic and when my speed drops to about 60 MPH the RPMs spike again from around 3K to about 4K. When the car gets below 60 MPH the RPMs drop again. If i let the car come to a stop the RPMs decrease normally without any other spikes.
Scenario 3 - Driving in sport mode (yeah buddy) around 20-30MPH it almost feels like the car is not upshifting and the rpms go crazy. jump from 2500 to about 4-4500 and finally the car lurks forward.
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Every now and then my headlights dim, flicker, and then go out. They will come back on only to do it again a few seconds later. It's only happened 4 times. After the first three times (all while driving on a freeway that was having work done making it but bumbier than usual) I took it to the shop. He tested the electrical system and could find nothing wrong. While he had my car he replaced a bad spark plug that had come off and fried a spot on the boot. I know the two things aren't related but the lights were fine for the next two months. The other night they did it again while I was on a very dark back road and it scared me to death. This road was a little bumpy and very curvy. I've had the battery and alternator checked and they are both fine.
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I have a 2015 IS350 FSport. I drive full automatic in Sport+ mode, and I notice whenever I decelerate, the RPM would spike up around 200rpm and back to normal within second. It is consistently when the gears are changing down. Is this normal?
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