Sputtering at Idle after change of sparkplugs

[billwert]

Well the other day I changed my Plugs and my oil. When I took the old plugs out 5 and 6 had oil in the gallies (valve cover seals leak). I soaked as much of it up as I could before I took the plug out. I then put in Autolite 3923's gapped to .029. Of course there was smoke on startup due to the oil in the gallies. But now when my car sets at idle; at operating temperature it sputters a little. Sounds like a backfire almost but it's real muffled. The tach hovers at around 600-700 rpm and when it sputters it drops to just above 500 for just a split second and hops back up to normal. I was thinking one of my plugs could be ruined from the oil ordeal and I need to install a new one or replace all six again. Only mods are K&N, AEM TRU Boost, and Bosch Bypass valve. Car runs fine except when idling. Any info and help is appreciated thanks Bill.

[jdub]

Autolite 3923 plugs are about 1/8" shorter than the stock spec...this can cause arcing due to the plug not fully seating on the plug wire. Had the the exact same thing happen w/ MSD wires. Swap over to NGK's and it will be gone ;)

[billwert]

Thank you jdub. Should I just get the plugs that a cross reference tells me to get or is there a specific number that works well such as 3923. Is gapping them at .029 a good idea or should I just follow TSRM specs?

[jdub]

NGK Copper spark plug 2330 (BCPR6ES) .032" gap
NGK Copper spark plug 3330 (BCPR7ES) .032" gap - 1 step colder
NGK Iridium spark plug 5689 (BCPR6EIX) .032"
NGK Iridium spark plug 5690 (BCPR7EIX) .032" - 1 step colder

The above copper plugs are equivalent to the Autolites.
Iridiums will last longer, but are more expensive and can "glow plug" after hard, long runs.
Higher boost = colder plug, less gap - .029" is a good start point.

Good info:
http://www.supramania.com/forums/showpost.php?p=471693&postcount=19

[billwert]

Thank you Much Sir. I greatly appreciate it. Bill.

[Rennat]

Wait... iridium will "glow plug"... ?

What are you better off running then, copper or iridium? I know copper doesnt last as long as iridium, but, how bad do the iridium glow plug then???

[chevyeater]

Wait... iridium will "glow plug"... ?

What are you better off running then, copper or iridium? I know copper doesnt last as long as iridium, but, how bad do the iridium glow plug then???

Been running Denso Iridiums in several 800+ whp cars for a while now. No problems "glow plugging" here. Get the correct heat range for your application.

Also, scrap that center valley cover and you don't have to worry about JIS plug height anymore.

[jdub]

Depends on what you do with the car and they "can" glow plug ;)

Like I said, long, hard (high speed) runs or a series of short WOT (drag racing) runs with little time in between. For the majority, it's not a problem. The other issue is iridium is not as effective conductor (both heat and electricity) as copper. IMO, copper is a better plug...it just requires you to change plugs more often. Either will work well though and the iridiums seem to have a better idle.

[chevyeater]

Depends on what you do with the car and they "can" glow plug ;)

Like I said, long, hard (high speed) runs...

Like back to back to back highway roll ons up past 160 at 30+ pounds of boost?

Copper does allow for a weaker ignition system to fire a denser charge than Iridium. It got annoying changing them every weekend though.

[IJ.]

Brian: In my case exactly like that :D

[chevyeater]

Brian: In my case exactly like that :D

What did you do grumpy?

[IJ.]

Just had a high speed miss that the only way I could stop it was switching to the same heat range coppers.

[jdub]

It got annoying changing them every weekend though.


That's why I'm running iridiums now actually...when I get the FFIM set-up installed, it's back to the coppers. With all the extra parts to remove gone, it'll be a snap to change plugs.

[chevyeater]

I have to run about a .003" smaller gap to get the same performance out of iridium plugs compared to copper. But then again, I've had a few sets running around in some crazy cars for more than a year without having to change them or losing any performance. Some of those cars were eating 2 sets of copper plugs in one night!

[jdub]

I have to run about a .003" smaller gap to get the same performance out of iridium plugs compared to copper.

Yep! Same here ;)

[IJ.]

I got down to 20 thou on the IR's and it was still doing it changed out to coppers and it went away so the only thing I could think of was it was overheating the tips.

LPG doesn't seem to destroy Coppers like gas/petrol so I get good service from them.

[chevyeater]

LPG is pretty hard to light though Ian. Those stupid Cavaliers I used to work on were slow as balls before they picked up a miss...

[Rennat]

For a mild setup with a MBC and an exhaust + intake, 1 step colder is good?

[IJ.]

LMAO at least mine isn't slow :)
(then again there's NOTHING off the shelf left in my fuel system)
(vids) (http://youtube.com/profile?user=IanJmk3)

[jdub]

For a mild setup with a MBC and an exhaust + intake, 1 step colder is good?

Stock heat range should work well for that ;)

[chevyeater]

Rennat- good rule of thumb is 1 range colder for every extra 100 hp. You could go stock or 1 step colder depending on how hard you push...

[7MGTEsup]

What would happen if you ran to cooler plug?? Say if you ran a 9 on a stock car??

[billwert]

I'm still having problems with my car. I changed Plugs and wires. All NGK. Plugs are iridiums. Now i'm buying a coil pack thinking maybe something is wrong with mine. If I still have the same problem I'm assuming grounding is the problem. Where is a good place to run another ground wire from the coil pack? My car missfires randomly going down the road now instead of at idle Especially between 1500 and 2000rpms. And sometimes when I WOT it builds boost and goes nowhere. Any suggestions? Thanks Bill.

[jdub]

Ok...so the idle problem was corrected with plugs/wires correct?

There is a ground from the coil pack plate already...it's a field ground and should not have anything to do with what you're getting now. If you want to replace it, just run a wire to an available bolt on the block or to where the battery ground bolts to the body.

Do you have any codes?

[billwert]

I guess so. There doesn't seem to be no missfire at idle. Now it's just while driving. Haven't checked codes since I replace my TPS about 3 weeks ago and that was the only code I was throwing. Will check them later today and post up if I have time.

[billwert]

Ok checked codes and are as follows; 41 and 34. Not sure what they are but am looking them up as we speak. Thanks Bill.

[billwert]

Just checked codes through TSRM. 34 boost leak. My accodian hose is cracked and that is the only hose I know that is cracked. Got one of those on the way. I have no trouble boosting though. I get plenty of boost just doesn't go anywhere (sometimes). Stays in overdrive and feels like i'm spooling a Semi truck turbo. Code 41 TPS?!! I just replaced ther frickin thing. WTF? So do I need to check my wiring? Like resistance of the connections maybe?

[jdub]

New TPS or used?

Did you clear the codes after you replaced it?
(could be a left over)

That cracked accordion hose is allowing unmetered air past the AFM. Are the rest of your IC hoses in good shape w/ tight clamps? Think boost leak ;)

[billwert]

Well it died on me one day and wouldn't start back. So I checked codes and it gave me a 51. I figure it was TPS. So I bought a brand new one and put it on and it started right up. I then Checked codes again and no codes showed up. Now when I checked them today 34 and 41 is what I got. I started my car with TPS connected and throttled up the car with the linkage and it cut out like usual in the 1500-2000rpm range. I then shut off the car and unplugged the TPS. Started the car and throttled it up again to about the same range and the cut out was much less noticeable. It was pretty much non existent. I could barely hear it. With the TPS connected you can watch the entire engine jump inside the engine bay. And yes all Intercooler pipes are tight and connected in good shape.

[jetjock]

1) Cracked accordion causing code 34 huh? I'd be looking elsewhere ;)

2) A faulty VTA signal from the TPS will not cause misfire at light throttle. It won't cause a no start either. You still need to fix it but the root cause of your problem lies elsewhere. Depending on the size of the crack it may all be in the hose.

[billwert]

It's a pretty big crack right at the turbo inlet. I guess i'll wait til my other one comes in and see if it makes any difference. I'll go over all my hoses again. Oh... the coupling that goes between the 3000 pipe and the throttle body is cracked. Would this be the cause of my problem??? And what would I need to get to fix the TPS problem?? Thanks Bill.

[jdub]

Well, there's your code 34 for sure ;)

Fix both hoses and I'm thinking a lot of your problem will resolve.

You do need to fix the code 41...most likely caused by VTA as JJ mentioned. That input to the ECU is used to increase injector volume at increased engine speed. I would check continuity of this wire to the ECU...make sure the wire is not shorting out somewhere.

[billwert]

Ok VTA is the plug going into the TPS or something else? I have a little knowledge of things but VTA is not ringing a bell. Thanks Bill.

(EDIT) Nevermind just figured it out. Thanks Bill.

[billwert]

Ok so I went out and checked the connectors in the end of the plug with a mulitmeter. The third connector which is silver in color has no continuity. I'm assuming this is the VTA. So what are my options? I'm pretty sure this is made into the wiring harness. Thanks Bill.

[jdub]

I assume you mean continuity between the TPS connector and the ECU connector. My '89 wiring diagram shows the wire as a blue w/ red stripe all the way to the ECU.

[billwert]

Well I checked the plug that connects into the TPS itself. So I should check the one that runs to the ECU instead? My results would still be the same would they not? Thanks Bill.

[jdub]

It's the wire in between that's of interest Bill ;)
First thing I would check is the connectors...after that, it's a matter of tracing the wire. This assumes the TPS itself is good.

[twistedshadows]

what he means is to check the wire by connecting 1 of the multimeter leads to the tps plug and the other to the ecu plug and check for continuity if u dont have any then there is a break in the wire also check from the tps plug to ground to see if u have a short
joe

[billwert]

Hmm... I see. The TPS should be fine since it's only 3weeks old. I won't have time to try any of this today since I have to work both my jobs. But tommorow or this weekend i'll give this a shot. Electrical stuff is not my cup of tea. Thanks Bill.

[jdub]

Get the accordion and TB coupler fixed 1st...that alone is going to make a big improvement.

[billwert]

I took the coupler off yesterday and didn't have a replacement. The people at the Toyota place couldn't come up with one. So I took a piece of some type of high dollar vulcanized hose (costs like $30 a ft.) And I put that on there. Car hasn't fell on its face since. Doesn't feel like I'm spooling a truck turbo anymore. I'm still waiting on the accordian hose to come in the mail. Thanks Bill.

[Supraman1313]

So what would you all recommend for an 87 non-turbo with a k&n air intake? I don't mind spending the money for good shit. I was planning on getting NGK's that run $7 a pop and wires for about $70 at Advanced Auto Parts. Anyone know a better place?

[billwert]

I ordered my wires from rockauto.com for like 40 something (don't really remember.) And I got the NGK iridiums. Some say it's wasted money and to go for the coppers b/c they are cheaper and better (or just as good or something). But I don't really know Jdub will be able to shed some light on the situation. He might even have a sticky on it somewhere. Anyhow back to my problem. I took apart the glove compartment today and will be pulling the ECU down to check the continuity between the TPS plug and ECU plug. This may be a dumb question but if I unplug both plugs I'll still get a reading correct? Thanks Bill.

[jetjock]

Well, if you're going to check continuity you have to unplug both. However you should be checking voltage because that's what the ECU deals with. Measure between VTA and E2. VTA should be around 300 mv at closed throttle and about 3.5 volts at WOT with a smooth and linear change between the two.

[billwert]

Ok well let me ask this to go ahead and get it out of the way. What if I get no reading at all as if it's dead? Am I gonna have to replace the wiring harness? Thanks Bill.
PS. Sorry to be a PITA.

[jetjock]

That you have the code means VTA is either open or shorted. Therefore you're likely to see less than 100 mv or more than 4.8 volts. Check it first then unplug the TPS and see if it changes. If it does the TPS is bad. If it doesn't you have a short or open in the wiring. Unplug both connectors and use an ohmmeter to confirm it. If that's the case you'll have to dig into the wiring, replace the harness, or run new wires. Course, it could be an ECU problem but that's unlikely.

Myself, I always open harnesses and repair them no matter what's wrong, even if it involves new wires and closing them back up. I consider any other form of repair a hack. Btw I'm assuming you've carefully eye-balled the thing to make sure it's not cut or melted as sometimes occurs near the back of the intake manifold. You could also try jiggling it with the meter connected. There's other things you can do too, like dummying the input and see if the code goes away. That would also prove the ECU good.

Oh, and you didn't waste money on iridium. Besides, the dinosaurs would be happy to know something useful came out of their demise ;)

[billwert]

I couldn't see no melting or anything of that sort so I'm guessing all is well there. Is it possible the TPS I just bought has already went bad? Anyways I'm off to bed as I have to be at work at 4:00am. I'll let you guys know tommorow what my results are if I have time and don't fall asleep lol. Thanks again Bill.

[billwert]

When you said E2 were you specifying the port on the diagnositcs box or one of the terminals on the TPS plug. I put my Mulitmeter set to 200m in the V/DC range. (May not have been correct to put it there). I had two blue wires with a red stripe on them. One was on the center connector of the ECU and the other was on the one on the side closest to the pass. side. The one in the center gave no reading and the on on the pass. side gave a reading of 0.11. That is with the black lead in the TPS plug on the top connector and the Red lead in the center plug and then in the pass. plug. So I may have done it wrong (car electronics are not my cup of tea) So please flame me in a nice manner if I have made another mistake. Thanks Bill. PS forgot to mention I hooked the old TPS back up and when I started my car the RPMS jumped up and down between 1250 and 2500 RPMS. I loosned the screws on the TPS and adjusted it till the RPMs were normal. Idling between 600 and 700rpms. When you gave it throttle it would just surge up and down. I gave it WOT and it went up to like 4300rpms and back down to 1500 and then back up. So I hooked my new TPS back up and it ran just fine except with the hiccup driving down the road. Sorry for the long ass post.

[billwert]

Ok I searched and found the TPS portion of the TSRM. And i'm 99% positive I screwed it up. So now I'm gonna have to make some more readings. I'm gonna go outside of my work right now and check it.

[billwert]

Ok so I took a reading again and using the TSRM as a guide I'm assuming the two gold connectors are VTA and E2. (This is with the key in the on position.) With my mulitmeter set at 20 in the Vdc range I got a reading of 1.13 on the gold connectors. The other connectors which are silver the reading was 6.41. I then switched my mulitmeter to 20k in the Ohms range and got a reading of 8.78 off the gold connectors. The silver ones I couldn't pull a reading off of. I changed it to the highest and lowest possible range in the Ohms range and couldn't get a reading. So I hope this will give the information needed. Thanks Bill.

[billwert]

JJ I found one of your old articles on the forums about adjusting the TPS. Could this help out my situation also?

[billwert]

Ok so I jumpered my TPS plug in E2 and VTA and read my codes and came out with this. 22,24,34,41,51. Then I plugged the TPS back in and had all but the code 51. So is the 22 and 24 coming from the fact that I had my TPS unplugged? And what about the code 51 going away after replugging in the TPS? Thanks Bill.

Edit: Pulled EFI fuse and all codes went away. Started car and shut it off and checked codes again and still nothing. Going to drive it now to see if anything reappears.

[billwert]

Ok so I lost the bottom screw to the TPS. I went to Home Depot and bought some hex head bolts to replace them. Got it tightened and restarted the car. The cut out is now not as noticeable but still there. Checked codes again and there are none. So is my TPS out of adjustment?? Thanks Bill.

[billwert]

Checked codes again tonight. And could not pull any. Still stumbling while driving and now sometimes it will idle rough and die. Gonna try a new TPS again on Friday. If that doesn't work guess I'm gonna buy an OEM one from toyota and if that don't fix it I'm not sure what i'm gonna do. Thanks Bill.

[jetjock]

A faulty VTA signal from the TPS will not cause misfire at light throttle. It won't cause a no start either. You still need to fix it but the root cause of your problem lies elsewhere.

What part of that didn't you understand?

[billwert]

I'll fix my boost leaks and let you know what happens. Thanks Bill.

[billwert]

I fixed my boost leaks and that didn't change anything. I got to talking with one of my buddies who works at O'Reily's where I got my New TPS from. He said come by and swap it out with another new one b/c he's seen bad ones come through before. So I stopped in swapped out the TPS's and now problem solved. So I guess the other TPS was bad. Anyhow thanks for putting up with me and my numerous questions. Thanks Bill.