Trying to Solve Fuel cut - at wits end - this one will stump you

[simpsons7s]

just ran with the stock AFM, and it spools alot slower and hits fuel cut at 8psi. so its not that.
Also, its worth noting that this car has run rich ever since I removed the emissions equipment long before I had fuelcut issues.
How did you eventually solve the problem on your setup?

I went standalone.:naughty:

I ended up throwing 2grand at the problem. No boost cut now though, and is better then ever.

My only other thought is that you have so many mods that your ecu can't handle it in its stock form so it fights back with boost cut trying to save your engine. You are trying to tune with an adjustment screw when you should be tuning with an electronic manipulator at this stage. The other problem is you don't have enough info to diagnose the problem. You really don't know what your true Hz signal is that your ecu is seeing, If you had a fuel computer of some sort you could log a/f ratio and boost pressure right up to when you hit boost cut and then know what is really happening. Since you have 580cc injectors you should have no problem hitting 25psi without boost cut. I know you don't want to throw a grand at a twelve doller problem but there is something to be said for spending countless hours banging your head against a wall.
One last cheap trick, have you tried spraing carb cleaner around your intake mani to check for leaks at idle?
Good luck

 

[Scot]

Ok this is going to be a stretch but did you check to make sure the previous owner did NOT install a FCD? The HKS FCD has twelve different settings and if it is not set to setting 3, for the 7m (I think), you will hit fuel cut because it is set for a different vehicle. (experience)

Again, just a pot shot....

 

[Pantaloon007]

Fuel cut isn't a simple value that once exceeded, triggers it. When playing with my 57 trim on the MAFT-Pro, I found I would hit FC @ 16psi @ ~4200rpm when I was running a dog rich 10:1 AFR. I was only reading about 1275-1300hz from the AFM, so I was confused at first.

Once I leaned back the AFR to around 11.8:1. suddenly I'm at around 1200 hz at that same 16psi @ ~4200rpm, and no more fuel cut at that point.

It's my understanding that FC is based on X airflow @ Y rpm. That means you can hit FC at a lower rpm, if your signal goes too high - and that 'too high' does not necessarily need to be 1400-1450hz.

I'm speaking from ignorance, being an old MKI/Corolla guy(MR2OC:icon_bigg), but it seems if you had a multimeter that measures Hz, and ran leads into the car, you could see when you aproaching FC w/o having to buy a $500+ unit. Such a meter can be had at Home Depot for ~$75. If throwing money is an issue, that might be easier to bear. Again, I dont know if the Hz figure is a measured value right off the AFM or a calculated one in the ECU. If I was to take a shot, I would say your problem lies in the lex AFM giving a higher than normal signal. Of course, boost creep would also induce FC and the gradual accel test is a great way to test it.

Also, Is there anywhere you can find the airflow(or Hertz) vs. rpm graph? For a guy whos about to slap in a BIC recirc DD, 3"catback, and a MBC set for ~10psi, and an eMnage eventually, it would be good to know.

Thanks for a wonderful thread devoid of texttalk, ridiculous theories, old wives tales, and general bullshit. Ive learned more in the last 45 minutes than in the last 2 weeks...

 

[Doward]

I tossed the idea of the MAFT-Pro at him, because he needs some sort of fuel management at this stage of the game

 

[figgie]

anyone has an O-scope to test and see what th AFM is reporting? Need to gather the frequency when Fuel cut is happening. And I do mean KNOWING not guessing

@ what RPM is it happening? Are you 100% sure it is not massive knocking and the computer is pulling timing?

 

[ArmandoP]

I know you don't want to throw a grand at a twelve doller problem but there is something to be said for spending countless hours banging your head against a wall.
One last cheap trick, have you tried spraing carb cleaner around your intake mani to check for leaks at idle?
Good luck

yeah, I have atleast a grand in head/wall banging by now.
Ive gone through 4 cans of carb cleaner doing that... and they were the 25% extra free cans too.

did you check to make sure the previous owner did NOT install a FCD?

Ive gone over 90% of the wiring in the car to make sure there were no loose or cracked wires rubbing, I probably would have noticed an FCD.

In all honesty, if you had a MAFT-Pro, this would be a lot easier to figure out (since you can read the frequency from the MAFT-Pro)

I will be searching for the benefits of a maft-pro compared to an AEM and the like. last I researched the MAFT Pro was a royal pain to get setup correctly. no?

I'm speaking from ignorance, being an old MKI/Corolla guy(MR2OC),

hehehe, Im still a mod on mr2oc. Remember the duel between Bill Strong and The Boostmonger??? I am the Boostmonger. Bill is still one of my better friends. yes, the same bill that tried to shoehorn a northstar in an MR2... :nuts: unfortunately he brought a pocket knife to a canon fight.

Im still working at the moment, butI will do these tests this afternoon and hopefully make some progress.
Armando

 

[figgie]

a basic O-Scope will give you the same information as the MAFT-Pro except be more useful in troubleshooting outside of the AFM

 

[Nick M]

A $12 Centech multimeter will read frequency.

 

[jetjock]

Thanks for a wonderful thread devoid of texttalk, ridiculous theories, old wives tales, and general bullshit.

If that were only true...

 

[IHI-RHC7]

Remove wastegate arm from from flapper and let us know if you still get a code 34. If you do, your AFM electronics are faulty or your wastegate flapper is seizing up when you're driving the car, but behaving nicely as not to get punished when you are inspecting it...
Just my .02 pesos...
-Jake

 

[Pantaloon007]

If that were only true...

Thanks for a wonderful thread devoid of texttalk, ridiculous theories, old wives tales, and general bullshit. Ive learned more in the last 45 minutes than in the last 2 weeks...

mybe i shud refrais...mstly dvoyd ov txtlk, etc...:1zhelp:

Armando: yeah i remember that whole deal, but there alot of good(read mature) people there and that is one great msg. board. Bill did act a bit godly, but when you have smileys dedicated to you, I imagine its gotta be hard to be wrong.

I hope you figure out the FC issue- I doubt there's anything more I can add...

 

[GrimJack]

Remove wastegate arm from from flapper and let us know if you still get a code 34. If you do, your AFM electronics are faulty or your wastegate flapper is seizing up when you're driving the car, but behaving nicely as not to get punished when you are inspecting it...
Just my .02 pesos...
-Jake

That reminded me! There was a problem with the wastegate flapper on the early turbonetics units. I remember reading about it when putting mine on.

It's never been a problem on mine, so I suspect they fixed it before I purchased mine.

 

[GrimJack]

Here's some info, from this thread: http://www.supramania.com/forums/showthread.php?t=21047

Dammit, why do they still use the old design. I taught ITS, and Turbonetics
how to fix that damned exhaust housing 4 YEARS ago. That shit is gonna blow
up another car (blew my 454rwhp MKIII up because of that thing, and Two of
Eric Verah's motors). Pretty much I can sell the LIPP housings because I fixxed
Brent's Turbo way back in the day when LIPP was buildling their new stainless
houseing.


Guys, listen VERY carefully. Take the turbo OFF the car, cut the old flapper
ROD out of the turbo, replace it with a 12mm bolt, reweld the flapper and
the wastegate arm, and stick it back in. OR contact me and I'll get Greg at
LIPP to get you guys the fix kits. They made those up years ago to fix the
problem you guys are having.

Jeff

 

[IHI-RHC7]

Interesting that you pulled from that thread, because this IS THAT TURBO
He bought it from Gixxer, but supposedly, he had ported the holly living piss out of the wastegate port and it didn't do it any more...
Strange to see it misbehaving again...

 

[ArmandoP]

Just tried the 4500rpm test....

my fuel cut problems happens between 5000-5400 rpm when Im at WOT depending on gear. I was mistaken by the 4500rpm. then again, its a pretty warm day today...

so, I tried going 3/4 throttle until 5000, then WOT and it hits fuel cut at about 5500rpm.
tried going 3/4 throttle until 5400 then to WOTand it hits fuel cut at 5800rpm or so.

all tests were in second gear as Im not trying to get arrested just yet and the highway is pretty busy right now.

Im letting it cool down and then Ill be pulling the wastegate clip to let it flap and try that.

anymore words of wisdom?

 

[IHI-RHC7]

My thought is that it's turbo related, since Gixxer had problems with it before you...
Did he run the turbo long after he solved the problems?

 

[ArmandoP]

whats even more interesting is this post by jtamulis...

the "rod" and "housing" are of two different steels. The "rod" expands different
when it gets hot, causing it to stick. My wastegate worked just fine OFF the
car. But I would have problems that it wouldn't build boost, and wouldn't build
boost, so I thought my diaphram was messed up on my turbo and drove to my
wife's mom's place in Canada. When I got there I went driving late at night, and
hit the gas, in 3rd, expecting nothing and it stuck the wastegate shut and
boosted to 30psi. I was impressed to feel the car go sideways at 80MPH tho!

I had not seen THAT particular thread but had seen the others where he talked about porting the wastegate and fixing the problem. my car is warm right now, Im going to try to move the flapper. brb.

 

[ArmandoP]

Well, I used a pair of long needlenose and STILL burned the hell out of my hand, but the wastegate appears to move freely even right after several FC inducing pulls in 2nd gear. damnit.

 

[Doward]

Open the wastegate completely and see if you still hit any kind of FC. You shouldn't build a lot of boost that way.

 

[GrimJack]

Well, it was a nice theory. Go spray down your hand with burn spray...

For my next trick, I will convince Armando that he should wear a raccoon hat while dancing around the car chanting.