Break up/Sputter after 15psi? Think i found the problem!!

[suprafanatic]

So i had recently just put a set of NGK copper plugs in the car, gapped to .028. I also have NGK wires. Car was running great after i put the new plugs in. I got some 110 octane race gas in the car, upped the boost and did some tuning with it. Car was running amazingly well at that point. That night we did a boost leak test and found some boost leaks and fixed those. After that the car would sputter or break up at anything over 15psi.. I changed the plugs about 4 different times with 4 different kinds of plugs and still have the same problem. Right now I have Autolite Plantinum plugs in the car. It runs very smooth up to 15psi. anything over that and the car sputters and has a power loss. Other than the plugs what could cause this sputtering? Also the wires seat down on the plugs very well.

 

[IJ.]

Sputter around 5000 rpm?

 

[suprafanatic]

yes around that. I can set the boost to right at 15psi and its perfect. As soon as i just up the boost a slight amount it breaks up/sputters.

 

[suprafanatic]

I havent gotten a new set of the NGK coppers yet cause they have to be ordered. Should i try the NGKs agian? after they sputtered i tried Autolite coppers, Bosch coppers which the car wouldnt even run with those in there. The Bosch made it constantly sputter, Then i put the Autolite platinums in and it runs smooth untill i hit 16+psi. So far the NGK coppers worked the best.. but what caused them to go bad? Or could it be another issue?

 

[IJ.]

What engine management?

 

[CajunKenny]

Are you monitoring your Fuel Cut Signal? What's it doing?

 

[suprafanatic]

using SAFC II, FPR, 255walbro, 550cc injectors, lex afm

 

[suprafanatic]

monitoring fuel cut signal?? one thing i did notice, at first it was sputtering at like 11-12psi.. then i leaned the fuel out alittle bit with the SAFC and then the sputtering moved up to 16psi. But thats all i could get out of it before it would sputter. Air fuel ratio is a 11.5 when it sputters

 

[IJ.]

So you have no way of adding timing in a map?

If not about all you can do is drop the plug gaps some more or go with hotter coils, it's just blowing the spark out around torque peak, I ran into this with the 7M a LOT....

For it to be so low I'm guessing the Coils are almost dead though.

 

[suprafanatic]

No way to add timing.. why would it randomly start doing that? It was boosting up to like 20psi that night before we fixed boost leaks. two of the injector O rings were leaking boost so i did replace those O rings. After that it just started sputtering up top... Could it be bad wires? or maybe a fuel problem? Or do you really think im blowing the spark out? My timing is a 10*. Also i did gap them down more, there at like .025 right now, and it still sputters. Are the Autolite platinum plugs bad to use? Should i get another set of the NGKs?

 

[IJ.]

Check the impedence on the Coils (TRSM has the specs)

Check the coils for cracks/carbon tracks

Test the leads

Yes it sounds like it's blowing the spark out, if you could adjust the map adding a few degrees in from 4500>5000 will usually cure it if you have enough octane overhead for it not to rattle.

 

[suprafanatic]

well as of right now im just running 93 octane.. So you were talking about the Coils being bad possibly? If the coils were bad or going out would that cause this probelm?

 

[IJ.]

Try checking what I've already suggested..... :nono:

There is a natural progression to these things, first you check a then b then c and so on.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=IG&P=10

 

[suprafanatic]

Ok. IJ theres one other issue i should mention. It might have to do with this problem as well. When ever i go out to start my car up when its been sitting a while it doesnt like to start up very well. Sometimes it takes a couple cranks before it starts and when it does start it idles terribly at like 400 rpms. Also, right after it starts if i touch the gas pedal at all the car completly shuts off. It does even attempt to rev up, it doesnt stumble, it just immediatly shuts down. If i let the car sit and idle for about 1 minute it starts idling better and i can eventualy give it gas. Do you think this problem could have a relation to the breaking up problem?

One more question.. what does detonation sound like?

 

[IJ.]

Try checking what I've already suggested..... :nono:

There is a natural progression to these things, first you check a then b then c and so on.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=IG&P=10

^^ seriously I'm finding this really frustrating.

You keep trying to go a>g>t>n....

 

[suprafanatic]

Found a new problem... When the car is on the fuel pressure regulator reads good pressure.. however, when i turn the car off the regulator pressure drops back down to zero pretty fast. Usually it holds pressure in there for quite a while. Would this possibly be the cause for the breaking up problem under boost?? If so what do i need to do to fix the FPR? Its not leaking anywhere that i can find.

 

[dbsupra90]

nate-

check the coils like ij suggested first. also make sure the plug wires are in the seperators.

where did you buy the walbro?

you still have that ebay bov? now that boost isnt leaking all over the place it could be the bov. since you still have the afm any boost leak can cause a problem.

and for the record, ngk coppers is where its at

seriously tho, go in order of checking things. if you check first, you can elminate that as the problem instead of poking around and guessing. usually easier that way.

edit: on a side note, that turbo is capable of some serious power. you need to look into upgrading the injectors as well as possibly the rest of the fuel system.

 

[suprafanatic]

I had checked the Coil pack and wires. All are within specs according to the TSRM.

I took the autolite platinum plugs out and took my NGK coppers and gapped them down to .018 as someone else on here had suggested. Still had the same problem at 16+psi. Took the NGK plugs back out and gapped them back to .024. Im completly lost at this point as to what the issue is. Coils are fine, wires are fine, plugs dont seem to be blowing out considering I have tried the plugs being gapped from .028 down to .018. Still the same issue with every gap tried.

Im going to order a new diaphram for my Fuel Pressure Regulator since it doesnt seem to be holding pressure properly. That may be the issue with whats going on with it breaking up as well.

 

[Poodles]

You're asking for help and completely ignoring the one person that's probably done everything you could possibly do to a 7M :: facepalm ::

 

[dbsupra90]

are you sure you are buying the correct heat range plugs?

and if the pressure is dropping off like that when you turn off the car, that sounds more like the check valve in the fuel pump instead of the fpr. you may have one of the knock off walbros if you bought it off ebay.