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hwvigo

Stumble on acceleration L28et

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How is it going my Z fam.

I am have a issue on my L28et i did not have with my last setup. And was wonder if I could pick your brains for some thoughts.

 

The car has a bad stumble on acceleration from any speed. It leans out but it always recovers after a few seconds. This is a issue on light throttle takeoffs from stop lights and in stop and go traffic. The car has even died on me a few time due to this issue.

Any help would be much appreciated!

I have attached a video of issue from a few days ago.

 

Specs of car.

83 L28et

Z31 ecu & maf by @Nismopik

76 intake ported to match TB

Webber big TB

T3T4 H-Trim turbo / H trim is a T04B wheel with a 70mm inducer, and 58.4mm exducer. @10psi

Turbosmart wastegate

Inovate boost control/ wideband o2

Supra yellow tops 310cc injectors

Areomotive 1:1 Fpr set at 28psi

Turbosmart bov venting atmospheric

2.5" intercooler

2.5" Exhaust

All new hoses for vac lines

New ngk plugs

Blaster 2 coil

Stock auto trans

Timeing set per FSM instructions @25°

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20170829_183558_HDR.jpg

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Posted (edited)

I'd have a look at your Acceleration Enrichment curve. The low rpm and Map thresh holds may be too low. 

Edit: Your AFR reading also appears to be far too Lean at idle. Should be in the 13.6 to 13.8 range with Batch Fire. However, I also hear what appears to be an exhaust leak. Have you checked for any exhaust leaks ahead of the WB O2 sensor? Those are an absolute NO NO and will give issues such as this. 

Edited by Chickenman

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Posted (edited)
On 10/1/2017 at 11:50 PM, Chickenman said:

I'd have a look at your Acceleration Enrichment curve. The low rpm and Map thresh holds may be too low. 

Edit: Your AFR reading also appears to be far too Lean at idle. Should be in the 13.6 to 13.8 range with Batch Fire. However, I also hear what appears to be an exhaust leak. Have you checked for any exhaust leaks ahead of the WB O2 sensor? Those are an absolute NO NO and will give issues such as this. 

Update.

Still not running great.

 

Car has no curve to adjust stock 84ecu .

Car has 2 o2 sensors.

a stock narrow band for the ECU, And a wide band installed for tuning.

The narrow narrow band os located i the stock L28et position 10ish inches post turbo.

With the wbo2 mounted 26" post turbo.

Pulled ecu codes nothing wrong there

No exhaust leaks at all on the car.

I gave it some more timing now set at 30° seams to like it more.

Still having the same issue once the car is warmed up blip the throttle and it stumbles.

Tested MAF per fsm passed

Maf is located 12" per turbo inlet , And filter is 18" per MAF

Car is still lean at idle even with fuel pressure bumped up to 30 psi at idle . No idea on that one.

Pulled pre pump fliter not clogged doing its job catching all the lil junk out of the tank.

Verfied injector to ecu compatibility.

Could bad gas cause this to happen?

 

 

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Edited by hwvigo

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The factory 260cc Fuel injectors are rated at 260cc at 36.5 pSI ( FPR vacuum hose disconnected and engine idling ). The Supra injectors are rated at 310cc at 43.5 PSI ( FPR vacuum reference hose disconnected and engine idling ). 

If ECU was calibrated for those injectors, you may need to raise you Fuel Pressure some more. IE: 43.5 psi at idle with Vacuum reference hose disconnected and plugged. 

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On 10/6/2017 at 3:04 AM, Chickenman said:

The factory 260cc Fuel injectors are rated at 260cc at 36.5 pSI ( FPR vacuum hose disconnected and engine idling ). The Supra injectors are rated at 310cc at 43.5 PSI ( FPR vacuum reference hose disconnected and engine idling ). 

If ECU was calibrated for those injectors, you may need to raise you Fuel Pressure some more. IE: 43.5 psi at idle with Vacuum reference hose disconnected and plugged. 

Got it FIXED!!

Thanks for all the help man.

Installed a new narrow band O2 for The ECU

Bumped the fuel pressure up to 43 static and BOOM all is ok.

And it hauls butt even at 8psi and 12 is nuts.

It's a bit rich under full boost so the ECU is being sent off to have the Nistune board installed soon.

 

 

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On 10/8/2017 at 2:14 PM, Chickenman said:

Good stuff!!!

How much does the Nistune mod cost? I really like the new Haltech 750. Purpose built for 6 cylinder engines with 6 injector drivers and 6 coil drivers. 

The nistune will run about 6-800 out the door with tune done. Tack on a extra 200 if i want to upgrade the maf.

 

As for the CAI I'm trying to work on something better with a friend of mine some fab work involved. I do not have space infront of the IC I spaced it out a good bit from the rad when I made my kit.

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