Topic: Intermittent Miss...HELP!

[reklund5]

Hey guys-

I've been having trouble with an intermittent misfire on my truck since completing the EFI swap last December.  Under light throttle (20-30%) cruising between 2300-3000 RPM, the truck misfires badly enought that the whole truck bucks.  I've pulled my hair out trying to find it, but haven't had any luck.  So far I've swapped the Cap, Rotor, Wires, and plugs with new Toyota parts from work, swapped the TPS with a (i think...) good unit and made sure the adjustment is correct.  I've run a  fuel rail cleaner through the injectors directly at the fuel rail, checked the timing and so on.  If I give the truck a little more throttle, the misfire clears up.  I suspected that the O2 sensor position may have something to do with it (way back under the drivers seat with my TRD header), but the misfire was there with the factory manifold on it too...  Fuel pressure is steady at 41lbs, and the filter is new.  It acts like a lean miss, but I can't seem to fix it. 

I've had the other master tech's at work look at it with me, and we haven't been able to fix it.  Any help that leads to a fix will be rewarded with a cold frothy brew!!
 
Ryan

[Suprarunner]

Ryan, I just had my nutz stomped by the same thing on my truck, when we got done with the Supra motor swap I had what sounds to be like a similar problem. I went throught he usual suspects that you have and we finally narrowd it down to the mass air flow meter. If you have access to TIS at your work look up the bench test for the unit and check it. Mine happened to be some wiring crossed up.

Hope this helps, if not you can pour the cold frothy one on my head... 

[reklund5 [OP]]

You running a 7MGE or 7MGTE?  I'm very familiar with the Supra motors...I've also got a 400HP 87 Supra.

The non turbo motors run a flapper door type MAF, similar to the 22R, right?  I've checked mine and richened the mixture by a couple of teeth, but everything seems to be working OK.  The donor EFI stuff all came from a wrecked 84 Celica- not that it should matter.  The only difference is the plugs on the coil and igniter, as far as I can tell. 

I'll check the TIS tomorrow... thanks for the tips!

Ryan

[Suprarunner]

Shoot no, I wish I had a 7m I'm rockin the 5m. AS far as I know all those old Toy's run flapper door maf's. Be carefull though, make sure the numbers on your maf match the injection/ecu your using. I mistakingly thought they interchanged and got muh ass handed to me.

[reklund5 [OP]]

I looked into things today...never had a check engine light, but put in the jumper wire anyway and found I have a code 11- short circuit in T terminal on the ecu.  I tried a different ECU just to be sure and its still there.  I'll start tracing my wiring tomorrow if things are slow at work...

[Suprarunner]

Keep me up on it, I've got 4 different mafs here that all make my truck run 4 different ways. if you have a fax number I have an old Cressida book that I can send you info that TIS might not have thats helped me.

[reklund5 [OP]]

After chasing some things down today, we think that I've got too many things grounded at one point, and the computer sees the low resistance beween the grounds as a short circuit in the TPS wiring.  Between myself and the other tech that I work with, thats the best we could come up with.  Using the Celica EWD as a basis, it shows grounds at the left pillar, the right pillar, and the valve cover.  I've got everything grounded near the ECU at the base of the right pillar, and a few things on the intake manifold.  From what we can tell, the grounds are backfeeding and causing the problem.  Tomorrow, we'll start tracing wires that were installed 6 months ago and try to figure out where we screwed up.  Who knows if that will fix the misfire, but hopefully it will clear the code 11 out of the ecu so we can start fresh.

Thanks for the offer on the Cressida stuff- I'll keep you in mind.  Luckily, the dealership where I work has been around since the early eighties, so we have a decent library of old books. 

Ryan

[GrimReaper]

Man does this sound like the problem I am having. I am about conviced that it's the valve timing from a head shaved to much.

Try retarding your timing and see if it clears up or gets better. If it does we proably have the same issue.

 Somebody told me every .040 is worth about 1 degree of vlave timing. To get mine to run reasonably well on super my timing is backed of 8-9 degrees. I'm at about 3degrees atdc.

 As best I can tell my head is at about 3.7810 (and that generous I may be less)
Your supose to use a had saver shim once you get down to 3.785. The little I can see of the HG it looks stock. I was going to make a cam gear with 4 degrees of advance (re indexing an old cam gear by drill a new hole for the pin) but concerned I would screw it up.  I'm probably going to order a DOA adjustable cam gear friday when I get paid.

About the only other thing I haven't tried is a new ignighter.  Trying to find sombody with one I can use to test.

 

[WHITE_TRASH]

Grim Ive read your thread on PBB, you are having one hell of a time with your rig!  I wish you luck, so far I think you'll need it.

[Marlin]

This may sound stupid-----

Have you removed the vacume line from the EGR valve and plugged the hose?
It sounds like you are getting too much exhaust in your fuel mixture.

I have found this on other trucks.

Marlin

[GrimReaper]

Thanks man. I'm ripping my hair out with this.

 I know somewhere I will find a machinest that can give me an answer but I just haven't found them. I hate throwing money at things but the normal stuff isn't working. Short of the ignighter I have tried everything else. The only thing that has ever made anny difference in the way it ran was backing WAY out on the timing. That's why I wonder if its valve timing. Valve timing would throw off the intake vacuum and that would mess with the AFM. The late valve timing would cause a misreading at the O2 sensor as well.  That's why I am nearly conviced that putting 4 degrees of timing in will get me closer to right BUT will it run on pump gas with that much off the head? That booger may well be pushing 11:1


 I did find a 87 RE runner for $700 with a bad tranny. Counting peneys and going to make the guy an offer. It's supose to run but might  have title issues. If I can clear up the title I'll use it to figure out what the hell is wrong with mine then rebuild the tranny and sell it.  That's if I can come up with the cash LOL.

[Prismo]

I have a carbed 83 tercel wagon that only runs with the timing way retarded. I have double checked everything a couple times & it is all correct. Advance the timing at all & it pings like crazy (dist is good, advance is good). Runs great where it is set now, so I just leave it & drive it (30K on engine this way). I too suspect a head shaved too much. Mine has no noticeable miss though.

[GrimReaper]

This may sound stupid-----

Have you removed the vacume line from the EGR valve and plugged the hose?
It sounds like you are getting too much exhaust in your fuel mixture.

I have found this on other trucks.

Marlin

Yeah checking the EGR was one of the first things I did.
TPS is new (it was bad and not retuning to idl)
New plugs, wires, cap, button, timing chain,
I have found several issues with the  head including the valves seated deap causing the rockers to be and excessive angle. Need to get a better caliper so I can get a more true deack measurment on the head.
I verified the timing mark is correct. It's within 1 degree.
Verified the VSS on the fuel pressure is working.
New ECM temp sender and swaped a cold start injector timer off a supre on it (same part number).
Ran it with the cold start unlugged to verify it's not firing all the time.
Does this cold and warm so doing it closed and open loop.


Frustrated.

Thanks for the reply Marlin. Once I get a K5 sold I'll be calling you for a crawler. Already have my second case. 

[Marlin]

Sorry, but I just cant buy the shaved head bit.

I know I have had this same problem and finally got to the cause.

Now, if I can only remember-------------

Searching for a good answer.

Marlin in Fresno

[GrimReaper]

That's exactly what Tim at DOA said when I tried to buy his timing gear last week and talked me out of it. He wants me to check the ignighter.

 I'm at a loss with it.

Had my buddy look at it and he's a ASE master mechanic for SAAB at Coprate running the Warranty Parts testing labratory. He is pretty good with Bosch injection. He was thinking injectors. What made him think that is we were Checking for Vacuum leaks with Carb cleaner And We poped the AFM up off the filter and fed it some carb cleaner and it smoothed out.
 I was thinking that as well till I retarded the timing and got it to clear up. Retarding the timing would only effect when the injectors fires not their spray pattern so that should rule it out. It would however make sure the valve was open before firing the injector by retarding the timing to match the valve timing.


Now here is another thing. I had Super in it and the set the timing by ear till it cleared up. Next take was mid grade and it got worse so I parked it so I don't plug the converter.

Plugs are on the fuel wet side. Till I backed off the timing I would on a very rare occasionally trip a O2 code. Once I backed it off that stopped.

I also ran it with the Knock sensor unplugged. Most say that will throw it into open loop...still did it.

Another buddy works at a shop and if he's working when I can get it down there I will throw it on his gear and check spark and see if his gear can hood to the ECM and give us some real time data. Unfortunaly we been working same hours 50 miles away frome each other for the last 4 weeks.

Again, thanks for the time and the brain power.

[reklund5 [OP]]

Ok, so after spending over 6 hours with 2 other Toyota Master techs, we cannot get the code 11 to clear out of the ECU.  I tried 3 different ECU's, so obviously I boogered something up when I hacked the Celica harness to install it into my truck.  Me and the other Master Tech that installed the EFI setup spent all day chasing our wiring and checking connections, etc. and still cant get the damn code out of the ECU, and it still Misfires. 

I'm officially LOST!

Ryan

[GrimReaper]

What year did the FI come off off? Code 11 on my 86 is TPS problem where it does't see idl t e2 closed with throttle closed. Looking at your TPS with the plug facing you there needs to be continuity between the bottom two pins.
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml
Nice write up on testing and adjusting.

If it checks out then pull the rubber boot off the plug so you and see the wires and check countunuity back to the ECM.

http://www.cygnusx1.net/supra/techtips.html That has some Supra 2nd and 3rd gen Service manuals. The FI is pretty close in most reguards. The trouble shooting info is much better then most.

[GrimReaper]

Ohh I was just looking at codes and it seems in 87 the code 11 could als be and indication of a Neutral safety switch ON. Wha did the this come out of? Was it a Auto? Might need to jumper that  on the harness.

[reklund5 [OP]]

Reaper-

Yes, the code 11 is the same as your 86.  I robbed all of the EFI parts off of a 1984 Celica.  I have already traced all the wires and even ran new wires directly to the ECU.  Somewhere in the system, the code 11 gets tripped.  At this point, I have NO idea where it is coming from.  I'm about ready to tear it all out and start over!

I've checked the TPS adjustment and even tried a new TPS.  The TPS has continunity on the two lower pins like it should.  I"m totally stumped.

Ryan

[GrimReaper]

Tried finding a 84 reference page on the celica online with no luck BUT according to the 4runner book I have it shows no code 11 on the 84 RE. It stops at code 7. Now on codes for 85 they show code 11 could also mean "Short circuit in terminal T with airconditioner switch on".

Thats two different year that show code 11 is something other then TPS related.  Since you have tested the TPS in depth I think the Celica is missing something that wasnt installed in the truck like that AC trigger or the Neutral safety switch.

  Every Toy I have palyed with has some extra plugs at the tranny. Basicly the harness has both Auto and manual. Then the ECM is installed with what the truck has and either a Jumper is used or the plug is left empty. The 7m supra motors were getting some trannys that required and gave ECM inputs but I doubt that Celica gets much more then just Neutral safety if it's a manual. I would find the tranny pig tails and if that celica had a Auto the switch normaly just goes to Ground. Try grounding it out if it's a single wire. Should not hurt anything. If it's a double wire then it may need a jumper if it was auto.

 If you want to meter it on most ECM related items 5v would indicate a ECM control circuit. You see 5v on it then trace it back.   

[reklund5 [OP]]

Thanks for the tips...

My buddy still has the shell of the car that I robbed the parts from...I'll check and see if it had a neutral safety switch.  Also, I've got whats left of the dash harness out in the shed, so I can see if I missed something.

You're right about the 84 not showing a code 11- it has to have been a 85 model to have the ECU flash a code 11, right?

Ryan

[Mike D]

Have you held a timing light on it when the engine misfires to see if the timing jumps or dies? have you tried a diff distrib?

[GrimReaper]

Thanks for the tips...

My buddy still has the shell of the car that I robbed the parts from...I'll check and see if it had a neutral safety switch.  Also, I've got whats left of the dash harness out in the shed, so I can see if I missed something.

You're right about the 84 not showing a code 11- it has to have been a 85 model to have the ECU flash a code 11, right?

Ryan

Well according to what stuff I have it would make sense that it's a 85 FI style. One thing for sure is Toyota has no problem making mid year changes. As an Example my 89 Supra mid year and I regualry had to get parts for 90 for stuff like output seals on the tranny. It's still quite possible that it was a mid year car and it got a revision for the 85 early so it's technicaly a 84.

 From the changes in the list of codes there were changes in at least the ECM in 85, 87, 88. Not sure that it would involve any major hardware changes so may still be plug and play so it may also be that a later model ECM was installed in that car at some point in its past. Look at the ECM and see if there is anything on it that looks like a date code. 

[GrimReaper]

Have you held a timing light on it when the engine misfires to see if the timing jumps or dies? have you tried a diff distrib?

On mine I I do not recall seeing that. THe Timing stayed prety solid when we were checking total timing advance.

[GrimReaper]

Sorry, but I just cant buy the shaved head bit.

I know I have had this same problem and finally got to the cause.

Now, if I can only remember-------------

Searching for a good answer.

Marlin in Fresno

Come up with any ideas?

Looks like I will have a little cash at the end of the week so I can buy parts again. I am open for any advice on this. I'm at a loss. That cam timing is the only thing that I can come up with. I'll get a good measurement on the head this week as well. If my other truck would sell I'm tempted to buy a 2L from Jarco.