3800 rpm popcorn machine

ok so at 3800 and around 5000 rpms in every gear ,everytime my 420a starts goin crazy i have tried looking around other sites and saw that its a common problem but no one has a solution for it not even my reg mechanic could figure it out specs on motor ;cold air intake , full exuast and rest unknown but should be stock ,, i have changed the coil pack checked plugs scanned cel codes changed cpsany ideas or has anyone even heard of this problem ... please help i want to start spending money on customizations for this car already !!

More explanation is needed. What exactly is the car doing? Is it something that happens all the time or every now and then?

well it happens all the time and sometimes even at a lower rpm but i can bank on 3800 rpms basically it just falls on its face and actually looks like it stalls the cel light goes off and all but it happens really fast

Is the car bucking? Making noises? Feels like its running on 2 cylinders? Sorry for all the questions its hard to give advice with not a lot of info.

Yes, the car is bucking at 3800 to 4000 rmp. Then it's smooth to around 5000 then it does it again. No abnormal sounds other than the popcorn popping sound from the bucking. Imagine it as a gremlin plugging and unplugging the ECU a few times fast.

Idk if it would be the same as my 4g63, but my car would do the same thing get to a certain rpm and just spit and sputter real bad then smooth out, i checked everything, my plugs even looked good, but i changed them just incase, and apparently it was my plugs, havent had a problem since

@SpoolMonster I think I will try that in the morning.

Even if it doesnt fix the problem atleast u have new plugs and can rule that out of the equation, also check ur plug wires, make sure they are in good condition, and check all ur grounds. a ground for the most retarded thing can cause the dumbest issues.

Thank you both very much for your suggestions, I will let you know how it goes tomorrow.

Yes, plugs are always a good thing to replace when having issues like this. If it doesnt fix your issue, at least you know theu are new and they are only a few bucks.

A friend of mine had similar issues with his 420a i believe. Between installing the aftermarket exhaust and intake, he would have a check engine light. Another culprate could be a bad o2 sensor, dirty air filter, clogged fuel filter, etc.

Does your check engine light stay on? I would take it to a parts store and have them read the check engine light codes for ya. Hell, do it when you go get your new plugs.

420a's are notorious for fudging coil packs. Check your with a multi meter. If its happening at wot, it won't be o2 sensor related. Check your cas, plugs and wires, and coil pack. If you change spark plugs DO NOT get anything other than NGK.

+2 on NGK.

Topic moved to problem diagnosis.

thank you for moving me to the correct area ... well new plugs (ngk) gapped @.44 no change so then i tried a different set of wires... no change . i tried different driving styles ... no change. so to this point i still am having the chattering problem and it is driving me nuts any other ideas /??

Check your cam angle sensor, crank angle sensor, and coil pack with a multimeter.

Do you have a haynes manual or anything similar? This will help you when checking the suggested above.

Check for vacuum leaks. I have a ton of them and they make my car run like hell. Im starting to get them worked out. May not be your issue but wouldnt hurt to check.

+1. vacuum leaks will do that. I have a ton on my 420a it sounds like a turbo goin down the road lol! if only...

How is it idling? If it idles at below 800 rpms then I doubt its a vac leak with the MAP system since your idle rpms would be higher. Have you scanned the codes at a auto part store? Most codes will read even after the light goes off. If you can get an engine code then it will help a lot because it could be any number of things.

Idle shouldn't be higher with a vacuum leak with a map. I know this because i completely blew an intercooler coupler off of my speed density equipped gst and it idled perfect and drove perfect with perfect afr. Wide open throttle was a different story.

onefast2gdsm wrote:Idle shouldn't be higher with a vacuum leak with a map. I know this because i completely blew an intercooler coupler off of my speed density equipped gst and it idled perfect and drove perfect with perfect afr. Wide open throttle was a different story.

Well of course it doesn't effect the idle if the leak is before the throttle body. After that... idle raises. Vac leak before that all you will get is noise and no performance effects.

Depending on where the leak is, yes. I think 420as are vacuum leaking beasts, both 420as I've owned have massive leaks. I can't find the culprit in my current one though. It doesn't affect idle or anything or cruising as far as sputtering, it just has no power. My money is on its spark related. Either coil pack or cas

Shake_Zulla wrote:How is it idling? If it idles at below 800 rpms then I doubt its a vac leak with the MAP system since your idle rpms would be higher. Have you scanned the codes at a auto part store? Most codes will read even after the light goes off. If you can get an engine code then it will help a lot because it could be any number of things.

This is not my area of expertise but i agree with you Jared. I also made the suggestion to have the CEL checked. This would easily point you in the correct direction. Like i said, i dont know much about the 420a compared to the 4g63 but getting the CEL checked is a definite good idea. Take advantage of the OBD2.

getting the CEL checked is a definite good idea. Take advantage of the OBD2.[/quote]

Ya I wish us 1g guys could get our CEL codes read at an autopart store. But noooooo, we gotta do it the old fashioned way lol.

Yeah but I will have to reinstall my factory ecu every time I need to pass emissions. OBD1 = sniffer.

Sniffer?

Yeah OBD2 checks in most states require a device to be plugged in underneath your steering wheel to read the ecu and make sure no codes are tripping. If you are a OBD1 they put a sniffer in your tailpipe and sometimes measure the idle to check emissions. It's crap you should be able to choose the sniffer if you want. My car would pass emissions but I wont have an ecu, now I got to make it so I can swap back and forth.

well i was going to get the cel scanned on monday but ... she died today ..just got back home after waiting for 2 hours for the tow truck and had to take off the front bumper which wasnt as hard as finding a way to fit it in the car .. i think it might be fuel pump related or sender because the kid i bought it from said if the car ever did not start to bang on the fuel pump which i never did when i had the problem i found that the wires going to the sender unit were a lil loose and just pushing them into the clip fixed the problem, but tonight that wasnt the case so back to the drawing board . looks like ill be driving my ford for a couple of days

im going to try and find the problem in the morning . any ideas on the best way to test fuel pump thinking of just getting 12v right to the pump with like a booster pack or something and go from there the clip might have just finally shit the bed for all i know

You should be able to hear the fuel pump while the car is running. I'd take it out and check if the socks clogged.

update ! ok so i got my booster back out and tried it again this morning and it seems there is no power going to the fuel pump i stripped back the wires and hotwired it to the booster pack and the fuel pump worked so no i have to trace down the short in the wire or relay or fuse or cutoff switch, thanks to all who have been helping me with the ideas and common things to check

Do a fuel pump rewire. I will make a tech article for it.

I want to do one as well but Im gonna wait untill I get an upgraded fuel pump first.

You will see gains even on a stock pump if you rewire it.

ok soooo i found thT THE ENGINE FUSE IS BLOWN AND tried replaceing it and i guess when i tried to crank the motor it blew again so now im trying to trace down the problem the first think i will do is disconnect the rfuel pump but i gotta get to the parts store and get a few more fuses ..

if the engine fuse was blown the car wouldnt run at all. I think you have a bigger problem on your hands than you think.

@ one fast yeah that is my problem now it wont start i have already unplugged fuel pump and coil pack to eliminate those as the cause and i still blew a fuse when i turn the key