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bad miss on s130 turbo cannot figure out Help??

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Ok, I went on a 250 mile one way road trip a few weeks ago, car performed flawlessly till 20 miles to final destination, Developed a miss like running in 5 cylinders all of the sudden..trouble shooted all logical things and nothing. Ended up bringing car back home on a trailer, and I will list all the things I have done so far and nothing. At first I thought I had some fuel injectors hanging up, changed a few seemed to improve but after a test drive back to running bad again.  here are the things I have  done,  

 

* all new spark plugs

* new coil

*new fuel filter

*new fuel pump regulator

*new fuel pump ( my gauge keeps saying 28 psi with vacuum , and 43 with vacuum hose removed from fuel pressure regulator)

*Car has always run on 28 psi even when running good   ( stumped on this one) manual says  46.3 psi

* did a compression test, all cylinders within the 10% +/- margine

*changed intake manifold gasket

* changed all seals to injectors, ( some where bad)

* checked pulse to all injectors ( to make sure they are getting signals)

*checked spark to all spark plugs ( all good and strong)

 

So I have been for the past  2 weeks looking and searching for the reason of the bad miss and I cannot find the corporate.

 

* I am beginning to think could the ECU be bad?

 

* I  Have a buddy that's a mechanic and Z fanatic that lives 2 hrs away that has been trying to help me trouble shoot the problem by phone or problems.....

* I checked the new spark plugs today and all but one are running really lean, except one that seems rich

 

Any advice from you Gurus here are welcomed  ...thanks in advance...Rob

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Bad hydraulic lash adjuster?  May or may not be applicable to your engine.

 

You should list the actual numbers for your cylinder pressure test, per cylinder, and also tell which cylinder has the darker plug.  You might find some things correlating to one cylinder.

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1. Quit buying parts. 

2. Troubleshoot.

 

Start with:  Clean the ECU, head temp sensor, and AFM pins and connectors.  Use Deoxit D5, followed by Deoxit G5.  Visually (and carefully) inspect all pins. 

 

If that does not work, just bite the bullet, and buy a new car.  It will be cheaper in the long run than rebuilding what you have by buying one part at a time.  :)

 

How do you know which cylinders were rich vs lean?  Can you post a pic of the sparkplugs? 

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Does the engine miss at idle, under a load, or both ??..

 

Have you tried isolating the miss to a particular cylinder??..

 

You can either try pulling one spark plug wire at a time and then re-connect it. or you can disconnect the connector to each injector one at a time. The engine idle will not change noticeably, on the cylinder that has the issue. Try isolating the engine miss. Then you can work on diagnosing what is causing the miss.

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rejracer, I will clean the ecu contacts, that is one thing I have not done. Most if not all other contacts have been cleaned recently and coated with dialectric grease. As far as knowing how do I know which cylinder is lean and which is rich? I pulled one at a time inspected and wrote  down findings.  As far as parts bought , I was given a list of parts to trouble shoot per my friend the mechanic and I followed it one by one , and replaced part only after each step he gave me had been followed..

 

 

 

@ dexter72, most of the time the miss is minimal at idle, sometimes it even sounds fine. but it's definite noticeable driving, and the longer I drive it the worse it seems to get. "very strange".

 

isolating miss, believe it or not, this seems a simple step as far as logic, but in this case it's difficult, I know this sounds bizzare.

 

and youre final suggestion. Man I have tried that I don't know how many times, every time I think I have nailed it down to the miss, It seems to get away from me, and not being the problem.

 

this situation is really Baffling not only me, but my certified mechanic friend....

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Have you adjusted your valves hot? It's not something that would do this unless something came loose on the way...but it will cause odd running.

 

What are the Ohm Readings of your plug wires?

 

You seem focused on fuel, but if the spark is weak, it will intermittently miss...and under some conditions the car will get worse as the wire degrades under heat of running or internal breakage raising resistance.

 

I have checked wires (relatively new brand name stuff) and four out of six failed simple ohm testing! Put on a new set, and it was like a new car!

 

Spark Plug Wires are CONSUMABLE ITEMS! Everybody seems to forget that. Check wires, report back!

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Tony, as I mentioned before....I did buy a spark tester and every one checks out after I installed a new MSD blaster coil. I just bought today new spark plug wires I"ll put them on tomorrow and we'll see what happens....I'll report on my findings.... I want to thank  all the peeps that have put their two cents in....Rob

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Here's where I'm at....when ahead and changed all sparkplug wires with a good set, Also bought the much raved about "de-oxide g5" very expensive too 17.00 for 5 oz can. , sprayed all connectors I could find, including pulling out ECU and spraying all terminals on that...started car, It seems to idle very nice, when I give it throttle I hear maybe a very small miss? I could not test drive it because it started to rain "and this baby doesn't get driven on wet surfaces".... will test drive tomorrow and report back...   I have been reading and reading and every article I can find online on similar cases, and some even go on saying that they pulled fuel sending unit out and had semi clogged strainer mesh....Maybe??? I also am very interested in seeing if my feed line from fuel pump up to the filter might be somewhat obstructed...? because as I have mentioned Im running only 28psi with vacuum on and 43 with vacuum off....why??? fuel pump is brand new and filter too....Rob

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You probably have a bad gauge.  Fuel pressure would affect all cylinders, not just one.  And, maybe it's a typo in your first post but pressure should be 36.3 psi, not 46.3, so 43 psi would be high.

 

The odd cylinder still looks promising as the corporate culprit.  Misses and dirty plugs go together.

 

Forgot to say - I don't see distributor cap on your list.  A bad or dirty cap can sometimes let spark jump to ground occasionally, giving a miss.  

Edited by NewZed

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Tony, as I mentioned before....I did buy a spark tester and every one checks out after I installed a new MSD blaster coil. I just bought today new spark plug wires I"ll put them on tomorrow and we'll see what happens....I'll report on my findings.... I want to thank  all the peeps that have put their two cents in....Rob

Sadly, I said to test the "WIRES". That involves a multimeter on "Rx1,000" and knowing how long the wire is...

 

This was read as "REPLACE"... After a purchased "tester" showed them "to be good"?

 

Replacement/Substitution is a GREAT way for a dealership to push parts onto customers...but it is not troubleshooting.

It's a rather expensive way to make your next best guess at what the problem might be.

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Newzed. you mentioned hydraulic lash? I have a turbo car has a p90a head non adjustable. My gauge for fuel pressure is fairly new and works fine, I got my pressure to go up to 38psi, better than 28  psi whish is what I was having with vacuum on.

 

I also ran some new ground wires from battery to engine, battery to chassis, and battery to intake where all the other grounds go to , to be sure its not a ground issue. I read this here on hybridZ and sound like an excellent idea.

 

Car now is idling really nice but under load, I still have a very noticeable miss.

 

Even took out fuel sending unit, to make sure I did not have a clogged screen.

 

I have been reading and reading and more reading all the articles here that pertain to engine misfire. As of now, I have pretty much done just about all that I can possibly do that is logical, and suggested by the  great members here.

 

I have tried test driving it with and without fpr vacuum ...no change..

 

I am at a loss right now, as I don't know what else to do?

 

I did notice I have a "spade" under the dizzy that nothing is connected to it....I have no clue what goes on there , My service manual doesn't really say either. I don't see any wire hanging either...

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" I have a turbo car has a p90a head non adjustable."

I am assuming this statement is derived from pulling the valve cover to check the valves already and finding out you indeed do have a later model 83ZXT with Hydraulic Lash Adjusters, and not the more common P90A Mechanical Head which is more common than most people think?

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WELL,  FINALLY FIXED!! Bottom line, tons of rust in the tank ( removed and cleaned it out. Took out about almost 1/2 a gallon of rust,) cleaned out all fuel lines and return lines , and lastly Injectors were Bad !!!! once I changed them all my problems went away..

 

I would strongly recommend Cleaning out youre Gas tanks if you have not already done so...

 

 

I want to thank to the many people that tried to help me out.

 

I hope this thread Can help someone else along the line...

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I doubt the injectors were "bad", more rightly their inlet screens had become plugged and their flow suffered.

Back flushing them in an ultrasonic bath usually restores them to perfect function.

 

It's a solenoid plunger...there is little electrically to "fail", but they are susceptible to clogging.

 

I hope you saved them, especially if they were JECS/OEM units, send them in to RC have them cleaned, and you are set with spares that are likely better than new stock available today!

 

Good to see it was finally resolved.

Edited by Tony D

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