SOLVED - Misfires + Sometimes Stalls. Also Timing Question

Jutzi420 · Post by **Jutzi420** » April 29th, 2005, 7:52 pm

Ok, here's where I'm at. New fuel pump, ignition wires + plugs ~2yrs old, plugs cleaned and re-gapped last week. external coil w/ HCI. Alternator tested good, Battery tested good. new belts on the alt and on the power steering. Plus Volt, Fuel PSI, and Oil PSI guages to keep it all in check.

After I let the car get up to temp I take it for a spin, if I mat the throttle over roughly 4000 rpm the car seems to missfire, I notice a slight dip in the tach, but no real change in oil or fuel pressure. On repeated attempts the problem seems to worsen to the point where it will stall out nearly every time, the car starts up fine afterward. Once the problem becomes this pronounced it will miss between 2500 and 3000 rpm, usually very minor tho.

Could this be a VRIS issue? O2 sensors? TPS?

And on a kind-of sidenote, I figured I should make sure the timing is bang on while I'm at it, but I can't seem to change it, no matter which way I tilt the disty it seems to stay the same: roughly one degree to the right of the 10 mark. How much should the timing change If you rotate the disty from one side to the other?

Tunes67 · Post by **Tunes67** » April 29th, 2005, 7:59 pm

On the timing issue.. you are using a jumper wire between TEN and GND on the diagnostic box prior to adjusting the distributors position right? After you then set the distributors position to where you want your initial timing to be.. (do this while the engine is running of course) then remove the jumper wire from the diagnostic box, before you shut down the engine. If you dont use the jumper wire, or if you shut down the engine prior to removing the jumper wire, the ECU will just compensate for any changes made to the timing.

Tunes67

Jutzi420 · Post by **Jutzi420** » April 29th, 2005, 8:03 pm

Hmm.... don't remember the manual sayin to remove the jumper while the engine was still running. I'll give it a shot. Thing is tho, with TEN and GND jumped, I can move the disty full to one side, and back to the other, and it doesn't seem to change the position of the timing marks.

Tunes67 · Post by **Tunes67** » April 29th, 2005, 8:17 pm

Now that is a bit strange... This is speculation on my part.. but If I were to get a result like that.. I would be thinking the distributor was having issues. Might check the manual for procedures on how to check your distributor. That might also be your other problem as well.
What year is your car?

Tunes67

Jutzi420 · Post by **Jutzi420** » April 29th, 2005, 8:22 pm

1992, with a 1994 ZE, and I had disty issues, oh, about 2 or 3 months back. so I gutted the thing and hooked up an msd blaster external coil instead. Ran fine like that until about 3 weeks ago.

Tunes67 · Post by **Tunes67** » April 29th, 2005, 8:26 pm

Not likely to be your MSD setup then.. those are usually bulletproof. Hmmmmm.. Well I can only be honest man.. Your issue is beyond me. I wish I could help. But I also dont want to waste your time trying out stuff that may not be applicable to your setup. Check back a bit later when some of the other guys around here with a similar setup have a chance to answer. Maybe track down your MSD wiring and see if you can check it out for proper function.. (though I doubt that would be the problem) In anycase.. Best of luck man.

Tunes67

jschrauwen · Post by **jschrauwen** » April 30th, 2005, 9:32 am

Pure speculation here, but when moving the the disty while running and Ten/Grd jumped and no change to moving timing mark - sounds like what Tune's said - ECU compensating. Not sure about removing jumper wire before shutting down though - first I've heard about doing that or is this the exception when doing timing? Perhaps a wipe of ECU memory followed by jumper wire then engine start and finally adjusting disty (rotating). If timing mark moves to desired spot, tighten, shut down, remove jumper. Just speculating here. Side note, I had something similar wrt missing at higher rpms and found criss crossed vaccum lines to be the culprit.

Pigman · Post by **Pigman** » May 4th, 2005, 12:19 am

Don't take the MSD out of the equation right away. They are plagued with problems on guys running them on B and F-bodies with the LT1. We had our fare share of crapped out units showing your exact symptoms on the 9C1 board. Swap in a known good disty and take it from there. Those dammed MSD's seem to crap out on a dime when they do. Made some 9C1's act real weird sometimes.

Just .02$ worth.....

Hope you get it fixed...

now...my MX-3 need a bigger engine dammit!...I got a spare LT1 in the backyard...anybody game enough...lolololol

hgallegos915 · Post by **hgallegos915** » May 4th, 2005, 12:30 pm

I had this exact problem and posted alot of times around it..no one could give me a conctrete answer..its your timing belt..period.. :/ if u havent changed it in a while. Mine does not back fire at all and also the ecu compensates for so much..it does not compeensay\te all of the timing lost. i\I can speak to you by experience on that.

Jutzi420 · Post by **Jutzi420** » May 9th, 2005, 9:21 pm

I wouldn't think it'd be the timing belt, it's not more than three years old. The fine folks at mazda tell me it's definatly an ignition problem, My HEI module seems to be fine, near as I can tell. I swapped it out for another just to be sure and it made no difference. I'm waiting on a new rotor as mine is not in the best of shape, cap's fine tho.

I wasn't sure before, since I never used to go much over 3000rpm until the engine was warm, but I've been hitting it harder on the cold side recently, and it definatly is less frequent when the engine is cool. the hotter the engine + the hotter the ambient the worse it gets.

Haven't made a whole lotta progress.... just waiting on that rotor to see what kinda change it makes.... if any.

MX-3 Money · Post by **MX-3 Money** » May 9th, 2005, 10:59 pm

I really don't have anything to tell you to try, but just hope you get it fixed. It hurts to see another ze'er with engine problems. Good luck man!

Tunes67 · Post by **Tunes67** » May 10th, 2005, 12:55 am

Two things.. apparently the ECU determines the amount of advance to use partially based on the temperature of the coolant so check your temp sensors.. you may have one bad or going bad (something to check at least)

Second..

Not sure about removing jumper wire before shutting down though - first I've heard about doing that or is this the exception when doing timing?

When I set my timing originally (and my idle) I followed the instructions in the manual verbatim.. at no point in the manual before it says to remove the jumper does it say to turn off the ignition.. I took this to mean that the car needed to be running in order for the changes made to be "Memorized" by the ECU. I dont know if this is correct or not.. what I do know is that if Mazda wanted me to shut the engine off before removing the jumper wire.. they should have put that in the instructions LOL

Tunes67

hgallegos915 · Post by **hgallegos915** » May 10th, 2005, 5:21 pm

well of course if its not the timing belt it is for sure a timing issie / ignition. 3 years? hmm shoiuldnt be that but you never know. Taking the top cover and checking it for it being stretched can never hurt. All Im saying this was the problem with my car and the timing belt only lasted around 3 years then again weather here is super hot... I changed it becuase I had no other things it could be. It did fix my problem. Check ecu codes, wires , plugs, disty. Also I would recommend change fuel filter and maybe changing the grade of fuel you use? (if you use regular)

Jutzi420 · Post by **Jutzi420** » May 12th, 2005, 6:36 pm

Ok... maybe related maybe not. Still haven't got my new rotor yet, but just something I noticed this morning.

I was scouting out how to test my TPS wednesday after work, but since I don't have the proper feeler guages it really amounted to not much more than disconnecting it and checking resistances at different spots. Long story short seems I forgot to plug the damn thing back in. I realised it after I made it to work this morning, I put the car in neutral and park, and my idle was high.... so I'm like WTF, I pop the hood and I see the harness is off. Car drove like a--, stuttering here and there, but not any different than it has for the past month.

Could it be bad? I was under the impression that if the thing doesn't work you'd be lucky to make it out of a parking lot let alone manage a 50minute round trip like I've been doing all week.

Can't check codes cause it seems my CEL is burned out.... not sure why I didn't notice that sooner.

So yeah, anyone have any genuine experience with their TPS dieing on them? lemme know.

Jutzi420 · Post by **Jutzi420** » March 31st, 2006, 4:49 pm

Ok, resurecting an old post cause I still haven't nailed the problem down. Got some more info now after almost a year of fighting with it. the problem points are at 2600rpm, 4100rpm, and 5300rpm (roughly, 4100 being the worst, followed by 5300 and then 2600). at all these points during acceleration the car seems to bog, almost as if I had down shifted it for a second then resumes it's pace. Under heavy acceleration it will jerk multiple times, 75% of the time resulting in a stall. It will always restart fine. Because these problem areas are really close to the VRIS points of the ZE I checked their opperation out and found them to function properly when voltage is applied. The problem is only apparent when the engine is under load, it never does anything funky when in neutral or with the clutch disengaged.

Since my last post I have tried going back to my K8 ecu. It ran better but the problem was still there (and it guzzles gas, so tha's no good). I swapped out my HEI mod for a rebuilt alternator, no dice, the problem's still there. Changed the coolant temp sensor, that helped to the point of making the car driveable again, it still stalls but right before this change it had gotten so bad it'd stall constantly. Last of all I replaced All the O2 sensors, and added an Aeromotive AFPR (factory FPR removed).

That's all I can think of right now, it's been a long haul so I may have forgotten a detail or two. That's the major stuff tho.

Can any sages out there wrap their head around this yet? I'm runnin out of things to replace. HA.