Hello guys, first of all, thanks for looking, and this is my problem: A little while ago my car started misfiring, so I replaced the plugs and wires. Still did, so I replaced the plugs again, and guess what, it still misfires. It is strange in that it is an erratic misfire, not a constant thing or on a regular rhythm, but just whenever it feels the need to do it. It misses more when it is up to operating temps, but still does it when cold. Could it be my coils or igniter? A bad ground maybe? I just had my alternator rebuilt (again) and the battery is less then one year old, so I don't think that it is either of those two. Please help me out, any suggestions or links to a thread that I might have missed would be very appreciated, again, I have searched, but I have yet to find an answer to my problem. Thanks for your time and patience. Josh

 

same with me

I'm going to look at adjusting the tps next

I'm also thinking it could be a ground but I dunno.

 

Try checking your plug wires and make sure they are connected properly and in the right place. Also make sure that they arn't grounding out somewhere. You could have gotten a bad set of plug wires.

 

Thanks for the replies. I'll have to look for some more wires I guess. Anyone Else? Josh

 

Weird ...my '94 Supra TT is doing the exact same thing right now. I've changed the plugs a total of 3 times, and taken them out and checked the gaps countless times. We've pretty much narrowed it down to coilpacks, but the 2JZ-GTE packs aren't very easy to be tested. Good luck!

 

It could be your harness. Mazda updated the coil harness. I think TwinTurboTeddy had a post about it a while ago.

 

I have the updated harness and I still have the thumppy idle beat.

 

Thanks for the feedback guys. Do you guys know how damaging this is? It can't be good, but do you think it might be moving faster towards blowing up because of this? Josh

 

I don't think its damaging to the engine its just very annoying to drive with. Find all of your grounds and recheck each one and make sure you hear a click when you put the plug wires on. Also look into adjusting your tps like I said before.
I'm pretty sure that it's the problem. I took mine off for a slow test drive and the car ran better except for the floating rpms.....

 

I'll play with the TPS this evening, along with the grounds. So you think it isn't particularly harmful? I'm looking to do more mods pretty soon (need for speed), and I would like to be relaitvely secure in the safety of increasing the exhaust flow and maybe the boost a bit, (boost will be monitered, as will the EGT and engine temps of course). Thanks for the input. Josh

 

Today, when I was disassembling my car looking for a mild coolant leak, I found a short tube from the air pump going (coming?) from the engine which had broken. I'll try to get a picture of it up. I will replace it shortly, look for the coolant leak some more, and let you guys know about it later. I spent this morning working on a downpipe for a 1998 Turbo Supra. I was "lucky" enough to have sheared off the first stud, and gotten half way through the second before my dad decided to just have somebody experienced do it for him. Laziness is a beautiful thing. Well, I guess that is all from here, any more suggestions? Anybody have experience with a broken air pump hose causing this sort of problem? Thanks for your time. Josh

 

i had a broken hose too on the air pump and that is not your problem.

have you tried an other set of coils? igniter? do you have a friend with which you can switch and try his?

are you sure the spark plugs wires are at the right place? leading and trailing at the right place? connectors on the coils at the right place? (one of my friend had that problem, after we installed the rebuilt)

 

I know a couple of people with FDs, so I'll have to try switching stuff as soon as I can. Too bad it isn't the air pump hose. I have checked the position of the wires several times, and I'll go look at it right now. Thanks for the information. Josh

 

Unfortunately (fortunately?) the wires are in the right places as per the 94 factory manual. I guess I'll have to pull the igniter and coils soon. Thanks, Josh

 

I played with the TPS, and raised the idle a bit, was around 800rpm, now is close to 1100rpm, this helped the lumpy idle some, but didn't solve it completely. I also found a little vaccum hose popped off, replaced that, and I didn't find a coolant leak around the turbos. I guess it was just some steam from the coolant/water boiling over. Josh

 

I hope you get it figured out
sequential is VERY hard to work with and to find problems

in fact, I've even been struggling with non sequential but I got it now

I wish you the same luck

PS a couple things you can try. Get a thick grounding strap and put it right on the engine block to the firewall (sand off the paint and clean the area first.)
Also, I took the coil harness ground and extended it and moved it to the firewall too. That was a recal, they took the ground off of the new harness because it was too close to the coils and could ark.

 

if the car is misfiring a lot at idle, i would think its because its running too rich. and i dont think it is a problem. just means that your consuming more gas then necessary, and probably have more latent hp in the car.

the tps, as snook suggested earlier, would control the richness/leaness. however, i would not recommend playing around with it. i would suggest to make sure that the tps voltage (for both ranges) is within specs. look at the manual for more info.

 

Be real cautious with "steam" from the turbo coolant hose area, DON'T just say oh well. As the coolant leaks from the coolant hose down the hard line that goes onto the turbo, the coolant dries into a greenish cruddy buildup. THIS CAN CATCH FIRE!. It is a concentrated hydrocarbon, and will burn. So really, look for that leak!

 

It smoked once, although it has been run while hot out several times since then. I thought it was a leak, but now I think it was just boil over that splashed near the turbos. I think that was it, and as I couldn't find any of the hoses/tubes leaking, so near as I can figure, it must have been boil over. I was just playing with the little screw that adjusts the idle. This hasn't done much to speak of. I guess I'll have to score and egt soon, or a wideband o2 and A/F gauge to get accurate measurements. Thanks for your comments and suggestions. Josh

 

Is the ignition coil supposed to be grounded? What's this harness update?

I'm having some misfire at idle and at high rpm's under load.

TPS is in range.

Please help! Thanks!

 

Yeah me too i have a lumpy idel and get get misfires under load in 4th and 5th. Ive replaced the the ignitor wires and the plugs themselves like 3 times. I checked the coils and according to mazda manual they are good. Could a misfire like that be in the tunning. with a PFC.
The other thought is that the ignition isn't strong enough. What about using that HKS twin power booster. Does that actually give any gain? From my understanding which isnt that great that a load misfire is caused by lack of ignition strength. If thats corrrect is the the only fix better coils/ignition booster. and help would be appricated and hope this could help someone mabe.
Thanks TJ

 

Yeah me too i have a lumpy idel and get get misfires under load in 4th and 5th. Ive replaced the the ignitor wires and the plugs themselves like 3 times. I checked the coils and according to mazda manual they are good. Could a misfire like that be in the tunning. with a PFC.
The other thought is that the ignition isn't strong enough. What about using that HKS twin power booster. Does that actually give any gain? From my understanding which isnt that great that a load misfire is caused by lack of ignition strength. If thats corrrect is the the only fix better coils/ignition booster. and help would be appricated and hope this could help someone mabe.
Thanks TJ

 

Gonna try grounding kit. Do you guys think Damians write up is good to follow or have other suggestions for grounding?

Should I ground the ignition coil? I read that an update removed teh ground because it caused arcing.

Let me know, I'm getting the grounding kit tomorrow.