Thread: Leaning Out: Part to WOT

I'm using a v2.0 MAFT with a 3.0" GM MAF the setting are in the factory state (450cc injector setting). I'm using 1000cc RCs with the a modded EEPROM (90 Turbo ECU) to accommodate the 1000s (Jeff O/Nick style). The MAF is about 6-8 inches from the TB bend. I tried searching around and couldn't find a solid answer. If I change the throttle quickly from part to full the car leans WAY out (21:1) and falls on it's face. Then if I let off and slowly ease into WOT it pulls like raped ape to 8500 with a good A/F. So, every time I shift in the next gear, letting up, and then mash it just leans way out.

It doesn?t seem to be RPM related.



Any ideas?

Bad tps, with a dead spot in the top range, what plugs are you running??

Originally Posted by OldDirtyNoSeven

Bad tps, with a dead spot in the top range, what plugs are you running??

I'm using new NGK BR8ES, NGK Stock # 5422

Unless I don't understand what you are seeing; the dip in the tps signal is between 2nd and 3rd when I let off and then floor it. After lastnight, I found that the problem only happens when gas it above ~4.5k when the turbo is ready rip. I can mash it all day from 4k and down, then it builds boost and takes off. Both the MAFT and MAF were new, I'll try a different MAM tonight.

Thanks

Unless the sudden surge of air charge is killing the spark,

I would try putting in a 6 or 7es plug just to see what happens, or its time to go with a MSD DIS-2 box

What is timing at? 8-10 btdc if so

try bringing it back to 5-6

Do you have access to a wide band 02???

Originally Posted by OldDirtyNoSeven

Unless the sudden surge of air charge is killing the spark,

I would try putting in a 6 or 7es plug just to see what happens, or its time to go with a MSD DIS-2 box

What is timing at? 8-10 btdc if so

try bringing it back to 5-6

Do you have access to a wide band 02???

Alright, I'll check on the timing and try the plugs. The A/F on there is wideband (Zt-2). I would think that if the spark is being blown out it wouldn't run so awesome?

Thanks

What does the A/F do when you jump on it at 4k

Also have you tried another ECU?

I have seen some mitsu ecu's drop spark signal when there is a drastic change in TPS voltage, why it happens Buschur said it may be a bad set of caps and the voltage ground loops between the two circuts or something of that nature.

Originally Posted by OldDirtyNoSeven

What does the A/F do when you jump on it at 4k

Also have you tried another ECU?

I have seen some mitsu ecu's drop spark signal when there is a drastic change in TPS voltage, why it happens Buschur said it may be a bad set of caps and the voltage ground loops between the two circuts or something of that nature.

It drops from 14ish to about 12:1 then stays there all the way to 8500. I'll try the ecu when I get home, my rootmate has the same burn on his eprom. That's going to suck balls if my ecu is bad. :?

Thanks!

I would add more fuel from 4k up

I like to run 10.5 to 11:1 I likle building engines but not the same one over and over again.

Originally Posted by OldDirtyNoSeven

I would add more fuel from 4k up

I like to run 10.5 to 11:1 I likle building engines but not the same one over and over again.

Haha yeah, I agree it needs to be richer. I was seeing a little knock. I'm also running 100% 111 leaded racegas.

This has gotten worse...

Setup:
OldDirtyNoSeven's old awd colt..
90 EEPROM ECU w/ extended maps and adjustments to match the injectors
(1000cc). Rev limiters both set to 8500 (sense we thought it was
two-stepping all the time)
MAFT (v2.0) w/ all the factory setting (set to 450cc)
3.0" GM MAF
SAFT-2
1000cc RC injectors
A-1000 pump
Aeromotive FPR @53psi

Stock 90 TB and intake manifold
2G ported exhaust manifold
FP 3065 turbo w/ new 44mm WG

"Built" (I built it) 2.0L longblock w/ leakdown of 1% 1% 3% 6%

30psi (not that I can get there anymore)
111 lead race gas


Problem:
When I first put the car together, it ran fine (spun all 4 in second
gear roll-ons). On occasion, when I stomped on the throttle at about
4k it would stumble and buck, then it would take off like crazy to
8500. It's continued to get worse... Now, any time I floor it it
cuts out and sputters/bucks. Even sitting in the garage, when I floor
it, it revs to about 4k (makes a few lbs of boost) and just falls on
it's face. Leans out from 12:1 to +21:1. After it leans out and the
rpms start to fall it will rev up again then lean out again...and so
on... Also does this if I'm driving around and just floor it in gear.
If I just keep it floored it slowly builds boost almost like an
anti-lag up to about 10psi.

Things I've tried:
1. My friend also has a colt turbo with a very similar setup --works
perfectly; supposedly the same EEPROM burn. So I swapped in his ECU,
MAFT, and GM MAF. This changed nothing.

2. Tried a 1G MAF, allowed the karmen Hz to get a little higher, but
still had the same results

3. I didn't have the RPM hooked up on the MAFT, attached that to pin
109. Nothing.

4. I installed a fuel press sensor on the rail so I could log it on
my Zt-2. Rises with boost, as it should.

5. Someone mention the speed sensor. I hooked up a scope to the
input at the ecu and I get a frequency that varies with vehicle speed
--looks ok.

6. Boost-leak test. I hear a little air rushing through the TB. I
squirted some soapy water in the area and a few bubbles formed around
the butterfly shaft (25psi). Can't imagine that would cause what I'm
seeing at about 3psi.

7. Checked the cam and ignition timing. Perfect

8. Replaced the plugs (.027") wires, coil pack, transistor

9. I hooked up an oscilloscope ot the air sensor input at the ECU.
The signal looks very clean, and reports the same frequency as the afc;
I was worried that the signal was being lost...

Conclusions I have at this point it time:
I had a friend burn the eeprom, even though I've swapped it I still am
a little skeptical about it.
Almost seems like it's hitting fuel cut.
Almost seems like a boost leak.


In the log file...if you notice the
TPS, the first part of the log I slowly ramp up the throttle till it
hits ~8k @800Hz. Next I just mash it, it flops around at about 4-5K
in the 1200Hz range.

http://xs121.xs.to/xs121/07460/colt_logs.jpg