Sr20det High Rpm Split Second Bog Down

[Autobacs]

OK Folks, hopefully one of you can shed light on this.

SR20DET is built, 740cc, 3076R, Walbro 255, 15 degrees timing, JWT ECU, FMIC and more. I'm running hard boosting at 18 PSI and engine is pulling strong then suddenly it bogs down around 6,500 RPM then picks up again. This bog down is instantaneous and last only for say half a second then the engine picks up again and redlines. My gut feeling and the closest thing I can think of is it seemed like somebody just turned off the power (electronic/electrical) for a split second and then turned it on again. Just put new NGK BKR8's with at .7 mm gap. This happens I'd say 1 times out 4 that I punch it hard. On my dyno runs, both boost and AFR's were good and even.

Igniter? Coilpacks? anything else? I'm sure somebody out there has experienced this. Hook me up with some info!

[nani]

should have gone with a stand alone...

[slider2828]

.7 mm gap? its supposes to be .030 gap? ....

Look at your plugs... see if you get any information off that... Could be coil pack as well or voltage to see if your system isn't grounding well... but sounds like a coilpack maybe giving out.

[MadScientist]

SR20 has 2 major High RPM issues that have to be considered especially when you have a high HP/ high RPM setup.

Floating Valves... what headwork do you have?
Solid Lifters? Solid Cams?

also...

Wiring; Coilpacks and Fuel Relay are not great but alot of people over look and dont notice it. You can use a Skyline Fuel Pump Relay (Tomei) to increase and stabilize OHM resistance. The Coilpacks are greatly effected by OHM resistan drop... Yashio Factory released a Tenka Wire Harness that decrease Volt drop. Also look at the SplitFire CoilPack system and the HKS DLI unit... I would only trust something that replaces the factory wiring... not just a piggyback or splice kit.

hope that hepls...

Peace
Drew

[Autobacs]

.7 mm gap? its supposes to be .030 gap? ....

Yes it does have .027 in gap.

Floating Valves... what headwork do you have?
Solid Lifters? Solid Cams?

Greddy valve springs and RAS with head ported and polished.

More Questions:

1. Can one coilpack giving out cause this? Or to rephrase is there a way to check which one or do you just replace all of them (considering they are 15 years old)

2. What did you mean by a piggyback or splice kit? Are you talking about grounding kits?

I'm ready to spend whatever it takes to fix it. I just want to do it smartly. Thanks for the inputs so far. I'm definitely getting a better idea although I'm not exactly clear yet on the plan of attack.

[spanishricer]

I had a similar issue after turning up the boost to around 19-20psi, and it went away after I installed the HKS Twin Power DLI. This was after checking the plugs and coil packs first and determining they weren't the cause.

[Autobacs]

Great. So how do you check the coilpacks if it's still good or toast?

[smelly240]

theres a resistance test...

[Autobacs]

Thanks. Did find it on the FSM.

[MadScientist]

Originally Posted by Autobacs

Greddy valve springs and RAS with head ported and polished.

More Questions:

1. Can one coilpack giving out cause this? Or to rephrase is there a way to check which one or do you just replace all of them (considering they are 15 years old)

2. What did you mean by a piggyback or splice kit? Are you talking about grounding kits?

Sounds like youhave a well thought out set-up but you aremissing a few critical parts that could caus ethe problem.
Check out Tomei and HKS for the Solid Lifters (Anti-Lash).
You will also need to upgrade the Cams to Solid type.
The HKS DLI system has a vehicle specific Harness... Splitfire replaces the harness and all the Coils... Yashio only replaces the Harness.
These are not Grounding Kits!!
Most Aftermarket units that increase spark... are not Vehicle Specific!!

just off the GT3076, 740cc, @ 18psi... you should be around 400???
You should deffinatly consider more head work, and the SplitFire unit!!!

-Drew

[Autobacs]

just off the GT3076, 740cc, @ 18psi... you should be around 400???
You should deffinatly consider more head work, and the SplitFire unit!!!

-Drew

Actually at 350 WHP. I do have all your suggestions in the back of my mind, Thanks.


OK now I did check the resistance on the coilpacks per the FSM and 3 read 0.9 ohms and 1 read exactly 1 ohm. FSM spec is 1 ohm. Is this Good enough or No???

I then checked the power transistor (igniter) for continuity as specified by FSM and I did not get continuity when I should have. I'm sure I did the test right and the result tells me the igniter is toast. This is an easy fix but my question is if the igniter is toast, is the car still supposed to run (which it does)????