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Discussion Starter #1 (Edited)
Here is a list of what I have:
OBD-I 95 Supra
DaveH kit (pt61) @ 7PSI
Stock injectors
Stock compression
Stock FPR
New cap and rotor
NGK Iridium plugs heat index 6 gapped to .32,
Stock plug wires
New O2 sensor, Bosch 12051 spliced into 1
2.5" IC piping and 30.5 x 9.5 x 3 FMIC
3" Exhaust, no cats
MAF in front of turbo.
SAFC tuned Hi-Throttle 70%+ for 11.5-11.9 AFR
No Lo-throttle adjustments
Innovate LM-1 Wideband
Cruising AFR 14.7-15.8
WOT AFR 11.5-11.9
Timing is +15 with no knocks (going back to +10 tonight)
Last compression check before going turbo 1200mi ago was
168-175 across all cylinders, car has 115,000mi
Idle is set at 950 and is rock solid with no more then 5-10 rpm fluctuation.

The car is almost perfect except I get a hesitation at partial throttle while excelerating. If the car is cold I can't boost at all except under full throttle, and when the car is warm, if I'm cruising and want to accelerate, under partial boost (1-5PSI) at 2500-3500RPM the car will buck and spit. If I give it full throttle it'll jump right up and run normally once the wastegate opens but anything other then that and it bogs.

I have no boost leaks (pressure tested to twice what I'm running, 15psi)
I have no vac leaks (pressure and visually checked as well).

I did a search for "hesitation" and the possible causes don't seem to make sense as if it were a fuel problem, wouldn't it also show up under idle and WOT and while not under boost?

Same for ignition as it runs perfect at WOT.
I have a cheap knock off BOV on the car could it be leaking under partial boost causing this problem, and is there anyway to test this without buying a new one, like remove it and just run with a pipe in place to see it that fixes it, or would that wreck the turbo?

Any help would be great as I'm stumped.
Thanks
Matt
 

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Over Medicated
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If your low low/partial throttle map isn't set up you may have something in it that is either dumping fuel or pulling a bunch out. Go into the low map settings and make sure they aren't set way out of the +/- 10% range. If they are reset them to 0% and start from there.
 

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Discussion Starter #5
kbprice - My lo-throttle settings are 0 across the board.
So I'm guessing by the advice here that we can indeed adjust the lo-throttle settings without affecting the ECUs operation? Can someone give me a yes or no on that?
Yes, we can adjust the lo-throttle without ECU problems.
No, we can't adjust the lo-throttle.

Remember I'm on stock MAF yet
Thanks
 

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Discussion Starter #7
Thanks.

I'm not sure but I think my MAF is actually taking a dump on me. I may have to either get a new one or go VPC if I can find one.

I tried setting the numbers on the low throttle and the car responded slightly but I'd have to add almost +20 to+30 from 3000-3800 RPMs to get the car running right. That seems like I have a problem somewhere else to deal with. So now I just have to figure out where.
 

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What is your reading on your wideband? That should show you if you have any holes in your tuning.
 

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Something I've noticed is small, but is a huge headache to find if you have it, is if one of the sensors/wires for crankshaft timing sensors have come off the block. I tried to figure out what was causing my random AFR, hesitation, moving timing, etc. Shouldn't take too long to check just to be safe.
 

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Discussion Starter #11
I'll check those, where are they located at (I don't have a manual yet). But I think DaveH may have given me the answer which I'm going to try tonight.

The 12v mod may fix my problem. He and I think that the hesitation in the 6-12v conversion of the fuel pump may be causing the lean spot to show up. I'm also replacing my fuel filter tonight as well as it has 60K or more on it.

The car is basically flawless at full throttle but at part throttle (6v mode) the fuel isn't getting there in enough quantity. But in 12v mode the car is working really well.

So hopefully that is the problem.
 

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hey man, im also NA-T.. i adjusted my lo throttle settings slightly.. But i was just wondering, how did you adjust the timing on the car?
 

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oVerb00sted said:
hey man, im also NA-T.. i adjusted my lo throttle settings slightly.. But i was just wondering, how did you adjust the timing on the car?
Upgrade to AEM :tag:
 

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I had this problem and it was o2's. It was a lean miss that took forever to figure out, so I bought one bosch and wired them up together.. it rarely happens now so I might try what akura said to fix it for good.
 

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Discussion Starter #16
You can adjust the timing on the NA by rotating the distributor. Jump the te1 and E1 ports in the diagnostic port under the hood. Then use a timing light.

bobmarley- I have a brand new bosch wired into one and that isn't helping. I think my lean spot is related to the BOV not functioning properly. So I'm testing that now.
 

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Discussion Starter #18
A Knock off Greddy S. And from what I can tell the BOV is functioning but i just think the diaphram may have a pin hole in it. I also just replaced all of my clamps with t-bolt clamps and that helped a little. I think I'm just about done figuring everything out.

I am going tomorrow to test a real greddy type RS that a friend has and is using now so that will pretty much tell me whether or not the BOV is working.

I know I shouldn't have gotten a knock off, but I wanted to see if it worked. I'm pretty sure it didn't so I'll probably be ordering a real Greddy RS on Monday. The only reason I'm going with the greddy is that is the flange I have already.
 

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Discussion Starter #20 (Edited)
Hi guys,
Well I tried the Greddy RS BOV this weekend and mine was definitely messed up. The RS blewoff correctly, and the car felt a little more responsive, but I still have the hesitation problem. I actually bought the one I tested so I know it'll work.

I'm thinking now that the hesitation may be related to something electronic.

I'm leaning toward the IAT, TPS or STA. The reason I'm think about these as the cause, is the idle will fluctuate +-50 RPMs if I adjust my idle above 900RPMS, if I hit the TPS hit my hand lightly it'll change the idle characteristics to run smooth, but once I hit the gas it'll return to fluctuating again, can the TPS be cleaned or anything?

I'm suspecting the IAT as the hesitation only seems to surface under cold car conditions. So that is a suspect as well.

I'm going to check the voltage and resistance on the parts this week and see if that is the problem. I hope I soon find it as I'm running out of parts to check.

After this I'm going to clean the injectors and run Seafoam through the entire car to see if that will help, then I'm totally stumped after that.
 
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