crazy rpm needle and acceleration problems

[Marcalap]

I have an intermitant problem with the ignition of my lx 1993. After some time (5-15min), the rpm needle will jump from low to high and the engine will misfire while accelerating. If the rpm needle is not jumping, everything is fine. I changed the coil for another used one from the JY but did not resolve the problem. The distributor is brand new and was changed 2 months ago. All wire looks OK. What should I look for now?

Thanks

[customchord]

So the dizzy is brand spanking new. Sounds like a igniter problem but if it is brand new then that one should be good. Try looking at all your grounds and battery connections.

[blacktrax]

So the dizzy is brand spanking new. Sounds like a igniter problem but if it is brand new then that one should be good. Try looking at all your grounds and battery connections.

^^^
agree..ignitor problem

sometimes depending on what Non OEM brand distributor you buy you get a push on style rotor instead of the OEM one that pushes on then gets fastened with a machine screw. To test it, take of the cap and see if the rotor is really loose by wiggling it.

[wed3k]

when you changed the distributor, have you checked the timing?

[Losiracer2]

and you replaced that distributor O-ring right? so there's no oil inside the dizzy? covering the new ignitor? b/c that definitely sounds like an ignitor problem, mine would jump like that at stoplights and sometimes kill the car.

[Marcalap]

The distributor was changed at a garage. I suppose he did is job right. I will try to bring it back next week.

I checked in the distributor and did not see oil inside.

[Marcalap]

Important note: The problem occurs only when the outside temperature is high. During night or rainy day, the car run fine. If I bring the car back to the garage, I doubt he will find the problem if the car can run fine 2 days straight.

[Night Wolf]

just open up your cap & see if theres oil in there. also see if theres oil on the spark plug cable tips. (on the tip that goes in the engine)


& btw is that like 3 meters of snow next to your ride?

[Marcalap]

Because of the incredible amout of snow, tons of salt must be put on roads to keed it in acceptable condition. For that raison, some rust proofing must be donne to the car. My problem with the car started the week after the application of pressurised rust proofing oil. So the possibility of oil infiltration in an electrical componant seem plausible, althought I never had this kind of problems before. I already checked in the distributor and it was clean. If it is an electrical ground problem, how should I proceed to diagnostic this?

Note: It was a good winter for skiing. Almost enough snow to do some skiing in front of my house.

[Marcalap]

At the garage, they borrowed me another new distributor. So I installed it then I drove 30 min without any problem. But Today, I got the same problems again. So, the external coil and the distributor are not the cause of the problems. The crazy rpm needle and the miss firing is definitely a sign of electrical malfunction. What should I look for?? At the garage, they don't have a clue. Important note: the problems occur when the engine is hot. I really need to find a solution fast. It's a big hassle right now to go to work.

Edit: I readed about misfire and jumping rpm. It seems that it could be a lot of things:

For a chevy with similar problems:
[...]I own a shop, and have seen this before. I have a feeling you have a bad set of spark plugs, or wires. If the miss wasn't there before, then you might need to check the air gap between the reluctor, and the pick-up coil. These run very close anyway, and if there is any wear in the bushings in the shaft, it will allow these to hit the pick-up coil, so you may want to confirm they are set to the proper gap, and remain there when you turn the distributor to the next notch. I have seen a distributor that had a warped shaft in it cause this problem. Also; the incorrect gasket under the distributor that is allowing the distributor to sit too low in the gear on the camshaft. Check the backlash with a dial indicator, and it should be around .005 - .008". When you turn the shaft, you must check each one with a feeler gauge (non- magnetic such as a brass one), and the gap should remain the same all the way around on each one of the fingers. If it changes, then the distributor is bad. Another thing that will cause this is a bad temperature sensor (sending unit) that is out of range, and the computer thinks the engine is either not hot enough, or too hot. I have even seen a sticking thermostat allow the temperature to climb out of range, and allow the computer to advance the timing to the point of a surge, or miss just like what you have. The wrong gap on the plugs can do this, and if they are old, and in need of new ones, they will tend to not fire a hot enough spark, thus creating a slight miss at low rpm levels. One last thing; A vacuum leak somewhere can, and will do this. Look at the EGR valve to make sure its not sticking, and test the throttle position sensor for any bad spots in the full range of movement. Check it with it unhooked with an analog type meter on the ohms scale. Move it slowly but at a steady pace to wide open throttle position, and watch for the needle to fall back, or jump during this test, and if it does, you have a bad sensor.. replace it. If this is a problem that only showed up after you changed the distributor, then it's 99% chance you have purchsed a bad distributor, and the air gap keeps changing. One thing that will confirm this is; Hook up a timing light, and watch it as you apply the gas slowly up to about 3,000 rpm's. You will be watching for the mark to start moving around as if its searching for the correct timing. The timing should move smoothly as you move the throttle up. If not, then something is not right with the distributor, and the reluctor may be hitting the pick-up coil at times.
Glad to help out, Good Luck!!!

[wed3k]

new distrubotr and spark plug wires?

[EJX_Michael]

How old are your wires? the electrical shielding deteriorates over time and it can cause the spark to jump wires. My moms CR-V had this problem. To check it spray some water on your wires at night (or in my moms case just look at them dry!) if you see blue sparks, replace them. Its quite an amazing sight to see the blue sparks at night.

[Marcalap]

Distributor is new and working. The wires are 3 months old. Can new wires be bad? I still have my old wires. I will plug them back to see if I got an improvement. I read on the net that a defective alternator can cause this kind of problems too. I think the alternator is 15 years old.

edit: Tested the old spark wires but without improvement. I don't have an extra external coil wire to test it. When I push the accelerator hard, there is no explosion at all. So it could be the external coil wire.

[Marcalap]

I asked for hints at 4 different garages today. They don't knows what to say except for a bad distributor. One of them mentionned the ECU or a clogged cat (lol).

[Marcalap]

I think that I have found the problem. If everything is good (distributor, coil, wire ground etc.. but the Tach is crazy and the engine misfire, maybe the 15 years old ECU is dying. When I smash on the ECU, the problems goes away for 1 to 2 min, if it happen again, I smash and it works again. Otherwise, I can barely move the car.

I will go the the JY this morning to find a immaculate ECU that still work.

Edit: It does work. So the ECU is not the problems. There is definitly something to do with engine bay temperature because today is a cold day. If I keep driving, the problem disapear. If I stop the engine or I stop at a redlight, the problem will come back.