at 8psi car sounds like a machine gun?

[Highlex]

After I swapped in my 7mgte it ran fine, then it developed this problem. When I am boosting and hit around 8psi the car looses all power and starts to sound like a machine gun or something lol, no CEL or anything... What could this be? I am super confused

(used to do it at 11, then 10,9, and now 8... problem is getting worse?)

I doubt it could be spark plugs, they are all new. I was thinking about getting an HKS Fuel Cut defencer but fuel cut shouldn't be happening at 8psi and there is no CEL either... Coil pack not grounded properly, it's missing the strap to ground it.

I have a MKIV TT Fuel pump but I did not bypass the jtube, I only want to run 10 psi anyways.

Two videos of the problem.
http://www.youtube.com/watch?v=hUqqvRplwWo

http://www.youtube.com/watch?v=4NA8MwWQl68

Mods would be, FMIC 2.5 inch piping, FULL 3 inch exhaust, boost controller set all the way down (like 10psi) new spark plugs, fuel filter, tps....

 

[boostin300]

Nice car..

I would say ignition breakup if its happening at high rpms. Not sure if you can regap your plugs, but get the right NGK plugs gapped at .26-.28 in there. Shouldn't be any higher than that. Make sure your coils are good, had one in a previous car that misfired occasionally. Replaces all the coils and it ran perfect after that.

 

[lewis15498]

Nice car..

I would say ignition breakup if its happening at high rpms. Not sure if you can regap your plugs, but get the right NGK plugs gapped at .26-.28 in there. Shouldn't be any higher than that. Make sure your coils are good, had one in a previous car that misfired occasionally. Replaces all the coils and it ran perfect after that.

+1 A while back there was a 2jz Cressida on Pinks, and it was doing the same thing. He changed the plugs and the problem went away.

 

[boostin300]

And also, if you can figure out for sure it's ignition breakup and you replaced the plugs at the right gap, coils and wires, I've heard of people actually using a HKS DLI and that solves the problem. Expensive way to do it though.

 

[lewis15498]

http://www.youtube.com/watch?v=fVhwIidu60U

Skip forward to 2:20 then 5:30 so you dont have to listen to simple jack (rich christensen) talk.

 

[Highlex]

By replacing the coils do you mean just replacing the whole coild pack? Yeah that makes sense im sure it's an ignition issue I will try my best to figure it out asap and post back here. Plugs are stock replacement issue.

 

[hvyman]

ngk coppers gapped properly. check the tsrm for proper coil testing.

p.s. weather or not your running before fuel cut a fcd is not a good mod. fuel cut is ther to save you.

 

[boostin300]

Yea do NOT EVER buy a fuel cut. Fuel cuts there so when your motor would start to get pre-det it stops it from getting real det. You keep going after its supposed to hit that fuel cut and you're likely to melt a piston or throw a rod or something equally crumy

Try and get a buddy with known working coil packs and see if its even the problem. Those things are expensive, like $65-70 each. Really though, NGK's gapped .025-.026 surprisingly fixes a TON of ignition problems. You should do your plugs with every oil change on a boosted car.

Might want to get new wires also if your current ones are really old. Sometimes when they get old and heated time and again they get tiny cracks and when the volts through em rise, they ground to the motor, not the plug. Also clean out your plug valley, Ive heard of guys getting water/condensation down there and shorting. That ones free

 

[thevork]

ngk coppers gapped properly. check the tsrm for proper coil testing.

p.s. weather or not your running before fuel cut a fcd is not a good mod. fuel cut is ther to save you.

yes check the coil pack and replace the plugs and just to be sure don't get the stock replacements but buy colder plugs. They work better than stockers when you have raised boost.

part number for ngk: 3330 BCPR7ES

 

[lewis15498]

Yea do NOT EVER buy a fuel cut. Fuel cuts there so when your motor would start to get pre-det it stops it from getting real det. You keep going after its supposed to hit that fuel cut and you're likely to melt a piston or throw a rod or something equally crumy

Try and get a buddy with known working coil packs and see if its even the problem. Those things are expensive, like $65-70 each. Really though, NGK's gapped .025-.026 surprisingly fixes a TON of ignition problems. You should do your plugs with every oil change on a boosted car.

Might want to get new wires also if your current ones are really old. Sometimes when they get old and heated time and again they get tiny cracks and when the volts through em rise, they ground to the motor, not the plug. Also clean out your plug valley, Ive heard of guys getting water/condensation down there and shorting. That ones free

+1 NEVER use a FCD.

You should be able to test your coil packs with a multimeter. There should be an explination and values in the TSRM, if not im almost postive the Haynes repair manual has it.

 

[Poodles]

-Misfire from junk in the spark plug galley (coolant or oil)
-Bad wires
-Bad coils
-Fouled plugs

Possible things, but keep in mind the spark plugs foul for a reason, more than likely in your case from running rich (MKIV TT fuel pumg without J-tube drilled out or bypassed).

Also, get a ground strap back on the coil packs, it's needed.

 

[Highlex]

I grounded out my coil pack, it helped for sure but didn't fix the problem. I ordered new spark plug wires, I will also drill out my J-Tube.

Hmm this sucks

 

[boostin300]

Do you still have the stock fuel damper in there? That things a biatch and should be bypassed.. they go bad randomly and restrict fuel flow a lot.

What's your idle fuel pressure? The stock regulator can go bad, aftermarket ones go bad every now and then too. Should be at least 40#, 43 is the stock pressure and works for most guys running a lot of boost.

It doesn't sound like a fuel problem though, but it's very possible it is. Do all the above and definitely get new plugs just because. If it's just coming from one cylinder it could be as simple as a busted plug. Either way it can't hurt to change the plugs when dealing with ignition problems and it's cheap. Make sure they're gapped .26 and make sure you do it right as some iridium plugs get messed up when you gap them. They will NOT come stock gapped at .26 , its usually a much higher gap. NEVER buy plugs and just drop them in, check the gap on each one or it could come back and bite you.

 

[thevork]

Do you still have the stock fuel damper in there? That things a biatch and should be bypassed.. they go bad randomly and restrict fuel flow a lot.

What's your idle fuel pressure? The stock regulator can go bad, aftermarket ones go bad every now and then too. Should be at least 40#, 43 is the stock pressure and works for most guys running a lot of boost.

fuel pressure at stock is around 32 psi, not 40.

I have it at 40 but that's with 550cc/lexafm and 14 psi.

hoewever I agree that this sounds more like an igintion problem than a fuel problem.

 

[dbsupra90]

mine sounded exactly like that when one of my injector seals came loose from the head. was causing a boost leak. wasn't like a normal boost leak, had good vac and ran fine. just sounded like in your vid when i would start getting up in the boost and lost all power.

 

[boostin300]

fuel pressure at stock is around 32 psi, not 40.

I have it at 40 but that's with 550cc/lexafm and 14 psi.

hoewever I agree that this sounds more like an igintion problem than a fuel problem.

Read somewhere it was 43#, you sure about that? 43 does sound high for stock though..

And yeah it could be a boost/vac leak somewhere. Depending on where it is it can throw off a sensor that effects another function. If its not that, probably would be ignition.

I might have read 43# on boost. either way, yeah I'm wrong. 30-40 at idle, usually lower 30's then rises when into boost. sorry about that.

 

[thevork]

Read somewhere it was 43#, you sure about that? 43 does sound high for stock though..

it says 33 in the tsrm. http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=A&P=8. with 6 pounds of boost and 1:1 rise it'll go to around 39 psi obviously

Anyway let's try to keep this ontopic and search these forums before you state things as a fact, just as IJ told you in another topic

 

[Poodles]

Do you still have the stock fuel damper in there? That things a biatch and should be bypassed.. they go bad randomly and restrict fuel flow a lot.

What's your idle fuel pressure? The stock regulator can go bad, aftermarket ones go bad every now and then too. Should be at least 40#, 43 is the stock pressure and works for most guys running a lot of boost.

It doesn't sound like a fuel problem though, but it's very possible it is. Do all the above and definitely get new plugs just because. If it's just coming from one cylinder it could be as simple as a busted plug. Either way it can't hurt to change the plugs when dealing with ignition problems and it's cheap. Make sure they're gapped .26 and make sure you do it right as some iridium plugs get messed up when you gap them. They will NOT come stock gapped at .26 , its usually a much higher gap. NEVER buy plugs and just drop them in, check the gap on each one or it could come back and bite you.

-Fuel Pulstation Dampener serves a purpose (why the hell do you think they put it on?)

-As already stated, your numbers for fuel pressure are way off.

-Stock gap should be FINE for his boost pressures.

-If you don't know, don't post in the tech section.

To the OP, when you pull the plugs, take pics of them. Plugs tell a LOT about what is going on with the engine.

 

[boostin300]

it says 33 in the tsrm. http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=A&P=8. with 6 pounds of boost and 1:1 rise it'll go to around 39 psi obviously

Anyway let's try to keep this ontopic and search these forums before you state things as a fact, just as IJ told you in another topic

True, I said I was wrong, and I already apologized.

-Fuel Pulstation Dampener serves a purpose (why the hell do you think they put it on?)

-As already stated, your numbers for fuel pressure are way off.

-Stock gap should be FINE for his boost pressures.

-If you don't know, don't post in the tech section.

To the OP, when you pull the plugs, take pics of them. Plugs tell a LOT about what is going on with the engine.

- Also true, it does serve a purpose. It stops fuel surges that cause turbulence in the fuel line. They do go bad though.. some people just bypass them and also have no trouble anymore.

- Yes my numbers were off. I did not check the tsrm before I posted and that sucks on my part. I apologized in a previous post.

- Stock gap should be fine but it wouldn't hurt to gap them down? A lot of people fix ignition breakup and ignition problems in general gapping down so why not do it if he's getting new plugs anyway?

- Thanks for the advice, lol

And true, generally if your running rich they foul up/turn black and lean turns them whiter.

I'll leave this thread before it goes nuts.

Good luck man.

 

[jdub]

True, I said I was wrong, and I already apologized.

- Also true, it does serve a purpose. It stops fuel surges that cause turbulence in the fuel line. They do go bad though.. some people just bypass them and also have no trouble anymore.

- Yes my numbers were off. I did not check the tsrm before I posted and that sucks on my part. I apologized in a previous post.

- Stock gap should be fine but it wouldn't hurt to gap them down? A lot of people fix ignition breakup and ignition problems in general gapping down so why not do it if he's getting new plugs anyway?

- Thanks for the advice, lol

And true, generally if your running rich they foul up/turn black and lean turns them whiter.

I'll leave this thread before it goes nuts.

Good luck man.

I'm not going to give you advice...I'm telling you in a very blunt manner.

Do not post in the Tech section again unless you have the TSRM backing you up. No more "I hear", "I think", "a respected member of the community told me", or any other hearsay in any way shape or form.

You've been warned...this is the last warning. There will be zero tolerance in the future.