Tuning a SMEC to run a SRT-4 2.4

[A.J.]

Since I know little about tuning I'm going to need some help. I didn't know anything about automatic transmissions but now I build them from scratch. So now it's time to learn how to tune from scratch.

Details about my engine so you don't have to dig through my build thread http://www.turbo-mopar.com/forums/sh...-Caravan-build

'04 PT GT Cruiser engine with an aluminum PT GT intake.
'89 SMEC with a 2.2/2.5 knock sensor threaded into the 2.4 knock sensor spot on the block between cylinders 2 & 3.
65PPH low impedance injectors.
Stock internals.
Balance shafts removed with an oil pan baffle put in it's place.
Ported/cleaned up cylinder head, by me.
Ceramic coated pistons, combustion chambers, valves, and exhaust runners.
S60 turbo with ceramic coated turbine housing and a TU 3" swing valve.
3" exhaust with a Magnaflow straight through muffler, no cat.
Log type exhaust manifold.
Late 80's Toyota Supra intercooler with 2" intercooler plumbing.
3.3/3.8 52mm throttle body.
NGK iridium spark plugs 2 heat ranges colder than stock.
3 BAR MAP
91+ epoxy coil

Today Harry (tryingbe) and I attempted to tune my van a little. I thought I was due for emissions but not until November of next year. We were getting knock between 5 & 10 lbs of boost. Mostly in cylinder #1 and sometimes it was retarding the timing without even seeing any voltage from the knock sensor. We tried to tune the pumping efficiency but when I took the wastegate rod off the swing valve I was still getting boost. Apparently my wastegate hole isn't big enough.

I'm open to any and all suggestions since I only know a little bit about tuning. I've adjusted fuel and timing for my old 2.5 and my Dad's 2.2 with success but those were only minor adjustments compared to what I need to do to this. Keep in mind I think I have the wrong stall converter in this. I don't know if that is going to affect anything.

A.J.

[ShelGame]

The 2.2 or 2.5 knock threshold isn't going to be close. Somewhere here, I think the 2.4 knock threshold is posted. I might have it saved somewhere, too. I'll have to look.

Also, the SRT4 timing is posted in the KC, or at least was. I'd use that as a reference at least.

Finally, I made a starter cal for Sean (I think it was, 1fastcsx?) to run a 2.4 on an SBEC. Look for that as a reference also. He made many changes to it, but I think most of the details are in the thread with the starter cal.

[A.J.]

The 2.2 or 2.5 knock threshold isn't going to be close. Somewhere here, I think the 2.4 knock threshold is posted. I might have it saved somewhere, too. I'll have to look.

Also, the SRT4 timing is posted in the KC, or at least was. I'd use that as a reference at least.

Finally, I made a starter cal for Sean (I think it was, 1fastcsx?) to run a 2.4 on an SBEC. Look for that as a reference also. He made many changes to it, but I think most of the details are in the thread with the starter cal.

I looked in the KC and couldn't find anything. After some searching I found the thread 1fastcsx started and has the cal you made for him: http://www.turbo-mopar.com/forums/sh...ck-electronics. I'll start with that, swapping over what I can from the SBEC tables to SMEC tables. Any other links you can provide would be great.

A.J.

[tryingbe]

Hm.. I wonder what happens if we burn a 16V TC SMEC cal and work with that.

[turbovanman²]

Hm.. I wonder what happens if we burn a 16V TC SMEC cal and work with that.

The knock curve might be close but timing is tame, I never looked at the knock table but did compare the 16v cals at one point.

He has to do what I need to do, hook up a listening device or some other form of knock sensor and actually listen for it, then tune. As I mentioned in his build thread, I had to add a lot of timing, I think you even commented on it as I posted a thread that I felt I was adding too much but most said who cares, give it what it wants.

[tryingbe]

AJ's van was behaving strangely though.

Knock voltage was below .2V most of the time and usually at 0V, when the ECU retard timing. It was only between 7psi-10psi when knocks appeaedr. According to the knock voltage table on the cal, ECU shouldn't retard timing at all at those voltage, yet the ECU was doing it.

1st cylinder is almost ways retard by 15degree or more
2nd cylinder retard to 2-4 degree
no retard on 3rd or 4rd.

When I retard the timing on the ECU by 15 degree at 7-10psi, then AJ can actually heard the engine knocking.

STRANGE!!!

[turbovanman²]

Cam timing out? Does he have the dizzy setup correctly? I am using a SMEC 8 valve cal tweaked for the TIII.

[tryingbe]

Exhaust cam was off a tooth, that is fixed now. Engine felt to have more compression, but van still feel slow with 10 psi as it did with timing off.
Distributor is setup on the intake came, we started at 12 degree, changed it to 8 degree. No change in knocks.

[GLHNSLHT2]

If you're still getting boost with the WG flapping in the breeze just pull the intake tube off the throttle body. It's not going to hurt anything for the 1 or 2 runs you do with it.

[ShelGame]

The knock curve might be close but timing is tame, I never looked at the knock table but did compare the 16v cals at one point.

The knock curve isn't going to be right. The block and head structure are still totally different.

[turbovanman²]

The knock curve isn't going to be right. The block and head structure are still totally different.

That's what I figured, so he'll have to make up his own listening device.

[ShelGame]

That's what I figured, so he'll have to make up his own listening device.

Or find the knock threshold curve from an SRT4. I know I've seen it...

[A.J.]

There was a thread awhile back that someone had come up with a listening device made up of a Volkswagon knock sensor and some speakers or something like that. I'll try to find that and build something.

EDIT

Found it. Post #50 http://www.turbo-mopar.com/forums/sh...l=1#post521051.

A.J.

[turbovanman²]

There was a thread awhile back that someone had come up with a listening device made up of a Volkswagon knock sensor and some speakers or something like that. I'll try to find that and build something.

EDIT

Found it. Post #50 http://www.turbo-mopar.com/forums/sh...l=1#post521051.

A.J.

I sorta built one, just need to finish it. I have a thread on alternative knock detection, some good idea's.

[A.J.]

I sorta built one, just need to finish it. I have a thread on alternative knock detection, some good idea's.

I'll get'er done this week. Now that I know what to look for.

A.J.

[ShelGame]

Are you using the stock SRT4 returnless fuel system? Or did you convert it to return type? 'Cause if it's returnless, you'll have to do some extra fiddling with the fuel tables to get the fuelling right...

[A.J.]

Are you using the stock SRT4 returnless fuel system? Or did you convert it to return type? 'Cause if it's returnless, you'll have to do some extra fiddling with the fuel tables to get the fuelling right...

It's a return system but I am using an SRT-4 fuel rail. I have the fuel pressure regulator mounted on the RF strut tower.



I was thinking, since I had to shim out my fuel rail because the injectors I'm using, depending on the thickness of the knock sensors, could I use the knock sensors as shims and then have one sensor monitor 1 & 2 and another monitor 3 & 4? Or would it pick up too much noise from the clicking injectors? You can see in the picture (if you can zoom) the mounting location on the intake, next to #4 injector. Or should i just use the stock location on the block between 2 & 3?



A.J.

[turbovanman²]

I would run them in the stock location.

[A.J.]

I transfered what I could from Rob's 1fastcsx SBEC cal to his turbonator v16.9 SMEC cal on MPtuner. It seems to have a little more get-up-and-go than what Harry and I came up with modifying my 2.5 cal.

I'm going to the junk yard tomorrow to get some VW/Bosch knock sensors to build a listening device.

A.J.

[zin]

I transfered what I could from Rob's 1fastcsx SBEC cal to his turbonator v16.9 SMEC cal on MPtuner. It seems to have a little more get-up-and-go than what Harry and I came up with modifying my 2.5 cal.

I'm going to the junk yard tomorrow to get some VW/Bosch knock sensors to build a listening device.

A.J.

You don't have to, or maybe even want to use an actual knock sensor, a microphone will do. I'm in the midst of building one of these myself, it's just a radioshak "hearing aid" with the mic removed/extended from the unit. Then epoxied to a piece of AL that I can sandwich between the sensor and intake in a kind of cantilevered fashion. The great thing about doing it this way is you can plug it's output into your car stereo and hear as loud as you like, or headphones can be used too...

http://www.autospeed.com/cms/article.html?&A=0353

Mike