engine hiccups under load

[Jesh]

I've had this problem a long time and would really like to get rid of it so I'm open to idea's. Anyways here is the problem... My car will drive absolutely perfect under all conditions and temperatures. But when I roll on the throttle fairly quickly as soon as the turbo spools and the car starts to pull, the engine will act like its hitting a fuel cut and lose power for about half a second. Then it will come back to life and with a fairly harsh jolt. If I slowly increase the rpms it will pull smoothly all the way to redline. This condition only seems to be a problem when the engine is under heavy load. Thanks in advance guys.

setup:
fuel pressure: stock
afr: under load 10.0- 10.5:1 (possibly to rich and flooding the engine?)
boost: 16psi
intake: stock with k&n filter
spark plugs: played around with different plugs and gaps but nothing helped, currently running bpr7es gapped at .28
ecm and electronics: none bone stock, checked the caps a month ago and they looked good, but I'm not ruling them out.

Once again... I'm open to idea's.

 

That's really rich & most likely the main cause of the problem. You also want to switch back to some #6 plugs & gap it about 24. No need to run 7's with your stock setup. You could also turn up the boost to ~18 psi. However do one thing at a time.

In this order - Plugs
Drive it, log it. If all is well then your done, otherwise move onto the next step.
Turn up the boost. This will help to lean it out a little.

 

[Jesh]

I like the second suggestion /ubbthreads/images/graemlins/devil.gif
But I'll go ahead and give the plugs a try first.

 

[Jesh]

Well I tried the plugs and nothing changed. So I turned up the boost to 18psi afr went to 11.0-11.1:1 but the problem is still there. Any more ideas?

 

[SouthCaliVR4]

check plug wire for arcing in the plug well.

How to do this. first pop the wires out & give the boots a visual, sometimes you can straight see the burn holes. Then put them back in but do not push them down to lock. start the car, pull up one wire at a time & watch the boot for any sparking other than just out the end. I do this by rolling the boot on the v/c. Any & I mean any arcing not coming from the hole on the end & the wire is bad. Lower light conditions help.

 

[1990ggsxnj]

Could also be a boost leak causing the fuel cut.

 

[Jesh]

Okay so I checked the spark plug wires and they look good. I also just did a boost leak test and nothing is leaking. I know either the fuel is cutting out or the spark, I'm just not sure how. Anymore ideas guys?

 

[mitsuturbo]

This is really a short in the dark, but do you have a factory VR4 maf, and not a DSM maf? FPSolenoid still being used, if so, is it working right? Is your BOV vented to atmosphere?

 

[Jesh]

I'm using the stock maf. fuel pressure solenoid is still being used, I don't know if it is working correctly or not. and my bov is recirculated into the intake. ... just realized something. I'm using a stock 1g ecm, not the original vr4 ecm. Could this be causing the hiccup?

 

[PreskitVR4]

My forehead just healed up from this brickwall of an issue. Mine was actually pretty stupid, it was loose pins in the ECU connectors. I was running a DSM ECU, with it laying on the floor. Everytime I would boost the ECU would stand up, pulling on the connectors. It was very violent but exactly as you described. /ubbthreads/images/graemlins/banghead.gif

 

[PreskitVR4]

Wow I just read your last post. Duh. Swap the board out of the 1g case into your GVR4 case, reinstall into factory location /ubbthreads/images/graemlins/grin.gif

 

[Jesh]

My ecm is mounted in the glove box with velcro, it doesn't move much at all. But I'll definitely check on the connector pins.

 

Look at the injector clips and make sure they are properly seated on the injector.

 

[Jesh]

Update: I installed a eprom ecu with ecmlink v3 and the hiccup is completely gone. Wish I could've figured out exactly what the problem was though...

 

[656of1000]

... maybe the caps were leaking in the original ECU?

I had a similar problem. And even though you fixed your problem, I'd like to share in case others look at this thread for answers for their own problems. My plug wires were bad, and although they looked fine when I inspected them, they would arc under heavy load. If your wires are more than a few years old, just pop in a new set. Even if its not the problem, its still a good thing to do. I've had excellent luck with the blue NGK wires.