Problem tuning for 25+ psi of boost

[A.J.]

I'm trying to tune my SRT-4 van for 25 psi of boost using MPTune and Turbonator v18. I have an AGP 46mm external wastegate and two springs in it that will give me 25 psi of boost with nothing else controlling boost. I installed a 4 bar MAP sensor because I'd like to run an even 30 psi of boost. Tryingbe and I got it tuned to 25 psi with no problems today. It pulled and ran great. I tried to shim the springs to get 30 psi. At about 27 psi it was blowing the spark out and then on another pull it cut out. Not like hitting over boost, like the engine dies. I move the throttle and nothing for a few seconds and then it comes back. Once I had not turned off table "OverboostFuelShutoffDisablePointFromMap Limp" because in "Table Description" it says, "Overboost Shutoff when Wastegate problem has been detected (should not disable this)" and the same thing happened, hit too high a boost level and no throttle response until I back off and wait. That table in now turned off by the way. I took the shim out of the wastegate and now it does it all the time at 25 psi when before it didn't. This also happened with the 3 bar MAP sensor. I thought my 30vac/30psi Auto Meter gauge might be off and I was reaching the limit of the 3 bar MAP. This does it with the Ostrich or if I burn the cal directly to a chip. I'm soooooo close to getting this thing on the dyno and then the track and now this pops up. Has anybody run into this before?

[shackwrrr]

Not sure where your gap is now, but just as a diagnostic measure, try making it smaller. The coil might not have enough voltage to spark with cylinder pressures that high. You may need to make the move to a CDI ignition since you are still using a distributor. DIS wouldn't see this issue as you would have more dwell time.

[A.J.]

Not sure where your gap is now, but just as a diagnostic measure, try making it smaller. The coil might not have enough voltage to spark with cylinder pressures that high. You may need to make the move to a CDI ignition since you are still using a distributor. DIS wouldn't see this issue as you would have more dwell time.

I think my gap is at .028" but that's not the issue. I experienced spark blow out at 27 psi of boost. Once I lowered it back down to 25 psi the blow out went away but that other problem of boosting and then losing throttle response until I let off and waiting was still there. I do think I need to upgrade my ignition system if I'm going to run 30 psi of boost.

[ShelGame]

I think my gap is at .028" but that's not the issue. I experienced spark blow out at 27 psi of boost. Once I lowered it back down to 25 psi the blow out went away but that other problem of boosting and then losing throttle response until I let off and waiting was still there. I do think I need to upgrade my ignition system if I'm going to run 30 psi of boost.

Distributor is on the end of the cam, right?

Can you datalog from the SMEC? I'd be curious to see the RPM trace. The dwell time and anti dwell time, too...

[A.J.]

I can with my Snap-on Solus Pro. I've never tried to save or download the information from it. Another way to describe what is happening is it's like the computer is shutting me down. It's like it's saying, "Okay you lunatic, this is WAY to much boost. I'm shutting you down (taking away control) until things get back to a manageable level."

[Force Fed Mopar]

Sounds like how the speed limiter works.

[85boostbox]

Sounds like how the speed limiter works.

This. What is your speed on the dyno. Aren't van smec limited at about 115 or 110?

[A.J.]

This. What is your speed on the dyno. Aren't van smec limited at about 115 or 110?

I haven't got to the dyno yet, this is all street tuning. I do the best I can on the street and then go to the dyno for squeezing out that last little bit. When I do dyno tune, he usually does 2nd gear pulls and the fastest I can do in 2nd is about 80 mph.

[ShelGame]

Was the distributor shutter re-indexed? To me, it sounds like a distributor problem. But, that wouldn't be boost-dependent, just RPM.

There are 4 overboost values; did you set all 4 to the max?

[A.J.]

Was the distributor shutter re-indexed? To me, it sounds like a distributor problem. But, that wouldn't be boost-dependent, just RPM.

There are 4 overboost values; did you set all 4 to the max?

My distributer is reindexed. I bought it that way from Rich Bryant. It runs great and was boosting great until I shimmed and then removed the shim from the external waste gate.

Yes all four overboost values are moved all the way to the right/off. Like I said, it's behaving just like the time I didn't shut off "OverboostFuelShutoffDisablePointFromMap Limp" but I'm positive it is off now.

[85boostbox]

What plugs are you running? Have you tried a different set. Or maybe the coil is weak? Wires? Sounds to me you need to start from the basics.

[85boostbox]

Have you checked plugs and condition. Looking at your post you deshimmed the wastegate back down to 25 and the problem persists. Sounds like you might have burned the plugs up.

[zin]

I'm leaning towards the waste gate, might be binding. And, it was the last thing to have hands on it before an issue arose.

I can see it binding slightly, then "popping" open, and binding a bit one the "open side" until the pressure difference is high enough to close.

I'd check the waste gate for binding /tight spots in it's travel. Might even feed it air pressure to watch to see its movement is smooth.

Mike

- - - Updated - - -

I'm leaning towards the waste gate, might be binding. And, it was the last thing to have hands on it before an issue arose.

I can see it binding slightly, then "popping" open, and binding a bit one the "open side" until the pressure difference is high enough to close.

I'd check the waste gate for binding /tight spots in it's travel. Might even feed it air pressure to watch to see its movement is smooth.

Mike

[A.J.]

I'm leaning towards the waste gate, might be binding. And, it was the last thing to have hands on it before an issue arose.

I can see it binding slightly, then "popping" open, and binding a bit one the "open side" until the pressure difference is high enough to close.

I'd check the waste gate for binding /tight spots in it's travel. Might even feed it air pressure to watch to see its movement is smooth.

Mike

It's an external wastegate. I can't apply air to it to watch it move.

What plugs are you running? Have you tried a different set. Or maybe the coil is weak? Wires? Sounds to me you need to start from the basics.

I'm using Brisk spark plugs because they are the only non-projection tips I could find. I really liked the non-projection tip NGK's that I had in my 2.5 but NGK doesn't make them for the 2.4 http://www.briskusa.com/. Coil is lest than a year old and is an Accel Epoxy coil http://www.summitracing.com/parts/acc-140021/overview/. Wires are as old as the coil and are MSD 8mm.

I got a chance to mess with it today. Warmed up, did two 25 psi pulls and no problem. Get to the shop to check spark plugs and spark plug boots on 1, 2, & 3 were just sitting on the plugs, they weren't snapped on. Checked plugs, plugs looked okay and are gapped to .028". Went to get gas, using a Grainger valve to regulate boost higher than 25 and got up beyond 30 psi, no spark blow out but that problem happened again where I lose power and throttle response. Go back to the shop and check for pressure leaks at MAP/Baro and Grainger valve cluster http://www.turbo-mopar.com/forums/sh...rainger+valves and found my second grainger valve to be leaking (the one not controlling boost so we decided to try just compressor outlet to wastegate. Held 16 psi. Put one grainger valve and got it to hold 28 and no loss of power and throttle control. The boost did drop off to 20 on one pull. I ran out of time. I need to do more testing. I thought it might be cal related but now I'm thinking maybe not.

I'm just trying to get it to hold 30 psi regularly and reliably. A friend recommended an HKS boost controller http://www.hks-power.co.jp/en/produc...evc/index.html and the cheapest I can find it is $310. I really don't want to spend the money on that right now if I can find another way to hold 30 psi. I really want to build and AC cooled air to water intercooler first.

[Force Fed Mopar]

I like my Greddy Profec B.

[A.J.]

I like my Greddy Profec B.

Doesn't that only go to 25 psi? The HKS goes to 43 psi. I don't "think" I'm going to go over 30 but at one time I also thought I wasn't going to go over 20 so I bought a 30vac/20psi gauge.

[zin]

It doesn't have the valve 's shaft exposed between the "head" and "body"/hot side? If it does, you may have to mark it with a Sharpie to detect its movement, if fully enclosed, well, that's a bit tougher!

Mike

[Force Fed Mopar]

Doesn't that only go to 25 psi? The HKS goes to 43 psi. I don't "think" I'm going to go over 30 but at one time I also thought I wasn't going to go over 20 so I bought a 30vac/20psi gauge.

I have a Profec B Spec II, and according to it's manual it can control up to 43.5 psi of boost.

http://www.greddy.com/upload/file/PRofec_Bspec2.pdf

[Ondonti]

How exactly are you differentiating between spark blowout and a complete lack of response? Maybe you are already suffering from blowout (undetected) at 25psi and then you are getting the plugs in a bad state where they just give up as you up the boost. First thing you should have done before posting was include what the plugs looked like.

[A.J.]

Spark blow out it when I'm getting popping out of the exhaust under high boost. In the past when I close up the gap and it goes away. Lack of response it when I hit high boost, boost drops off (down to zero) and I get zero response from the throttle/gas pedal like the computer is shutting me down.