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Discussion Starter · #1 ·
Hey guys, looking for some help.

I've got a 1JZ swapped into a BMW, and I'm having an issue I can't seem to solve.

The car idles/free revs just fine, but under load, if I mash into it, it will rev to what I believe is about 3k, and as boost grows, the car will sputter and jump pretty bad. If I gain revs slowly without building boost, the car will accelerate, but it still has hesitation and spitting.

I was assuming it was entirely a boost issue, but as I said, it happens without... but it is primarily when it starts boosting. It's right as the car is about to "take off", it just pops, almost like a backfire, hesitates, and stops accelerating.

Any insight would be greatly helpful.

Thanks,

Mike
 

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plugs, check those first. what are you running/how long they have been in there, and whats there gap.

since your swapped, factory computer or aftermarket?
 

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Discussion Starter · #3 ·
I changed the plugs and the issue stuck around. They're gapped to .28

I'm running the factory ECU, for an A/T car. I'm running a 5-speed. I don't think that's the issue though.
 

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I'm not to sure about factory computers, fuel cut?
 

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This is the EXACT same problem I have. Put a 1jz into 91 4x4 4runner. According to my tach it is about 2700 for me most times. In park it throttles up fine, but like you said under load it sputters constantly, has no pick-up what so ever. I installed an air/fuel gauge and saw that with every jerk of the stutter it leaned all the way out. So obvious thought was wiring so i checked and rechecked and insured good continuity. Next was the MAP, so i replaced it, then thought it must be the TPS... nope. Tried the O2 after that. I am at a total loss. On pulling plugs i have HEAVY carbon build up but all uniform. A/F shows rich at idle, good up to 0-psi then leans out with rapid jerking. If nothing else maybe i have helped you on what not to try. Please let me know if you solve this as it has help me up for over 4 months.
 

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possible ecu problem?

if my car shudders or acts like what you guys are describing my plugs are either fouled or there gap is to big. did you try narrowing the gap. My friend runs a bkr7e with a 22-25 gap. could try that. then possibly pull the computer and open it and see if it looks fried. if you have replaced everything and have nothing else to replace. it might just be a ecu.
 

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Discussion Starter · #8 ·
possible ecu problem?

if my car shudders or acts like what you guys are describing my plugs are either fouled or there gap is to big. did you try narrowing the gap. My friend runs a bkr7e with a 22-25 gap. could try that. then possibly pull the computer and open it and see if it looks fried. if you have replaced everything and have nothing else to replace. it might just be a ecu.
I'm on BKR7Es with a .28 gap. It might not be perfect but it certainly wouldn't cause the car to do what it is doing so violently. The plugs that are in there are good, they have about 2k miles on them.

I've tried everything I can think of except the ECU. I've tried a different MAP sensor, igniter, TPS, etc.
 

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The Hard Way
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Thanks. I will open up the ecu today. At this point i hope to see something bad, just so I can know what's wrong.
 

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Im having a similar issue. bad hesitation till 3.000 rmps and 5lps of boost my af goes below 18 then suddenly it takes off fine and afr goes to around 12.
 

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wondering if there was ever a resolution to this i am having this issue right now with no leads. i put new plugs in today car worked great for 10 minutes then started doing it again
 
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