Very rich on cold start

[turbors89]

Okay I really need some help Ive been trying to chase down this problem for awhile to no avail. I recently just got the car running after changing the whole topend and on coldstarts the car idles real rich black smoke and all and sounds like it has a huge cam. It was doing it before the overhaul also and I figured it was because it had a Fwdp f4 cam in it lol. I just checked the codes and I have a code 52 which is for O2 sensor which I just changed out when I did the rebuild with a NTK unit. Its no doubt always running rich I took it to inspection and failed miserably. I have a feeling it might be my injector harness? Could it cause the car to do what its doing? Its in pretty bad shape but idk if it can cause what it does. I am also getting supposibly alot of knock idk if its false or not i can be cruising at a certain rpm and the light will come on and stay on until I let off or accelerate more and it will do it under boost also and I can feel it loose power when it happens. Its no doubt not running like it should its not making the power it should be and im stumped. The car has,

1989 2.5
2 Piece intake
+20s
Big valve head
ported exhaust manifold
Turbonetics Super 60
Socketed smec with custum cal

I quadrupal checked ignition timing and its dead on 12 Degrees and cam timing is straight up. I know when I ordered the cal I selected for a IAT sensor and I wired it up yesterday to no change.

[PunKid]

how is your MAP sensor? is it plugged in and has a good vacuum source? Anytime my car starts running pig rich at idle I alway find my map sensor hose has popped off. this would also explain why you have knock under boost.

[tryingbe]

What number does the wideband says? If you don't have one, buy one.

Who did the cal?

[cordes]

It probably needs some fuel taken out during cold startup. If it's blowing black smoke and running rich only during that time, I would think cal issue first.

[ShelGame]

Is it rich always on idle? Or only on cold start?

Which 3-bar MAP are you using? There are some of the cheap Chinese eBay 3-bar's that have a problem. They don't read the right voltage in vacuum. In boost, they seem OK, though. It causes exactly what you're getting - rich idle.

If you have an actual GM or Mopar part, then it should be OK. An easy way to check is to put a voltmeter on the MAP sensor signal wire and see how many volts output you get at idle. See post #5 on this thread from CSXtra...

http://www.turbo-mopar.com/forums/sh...bad+map+sensor

[turbors89]

I do have a wideband I just havent had time to get the bung welded in but I will have that done asap. I know its very rich on cold I can tell by the black smoke lol but once it is warm it runs fine but you can still smell it. I got the map sensor straight off FWDP but I will check out the voltage anyway. Thanks for the tips.

[turbors89]

Alright well finally getting somewhere I belive. I was out the other day looking at my injector harness and it pretty much fell apart. Wound up changing it same thing,actually it was even worse. Well brainstorming mode happened I wound up coming up with the idea to try out the stock computer. Plugged it in left the 3 bar and plus 20s in keyed it over fired right up no surging and it ran great, better than it did in a long time. Now im wondering what could cause the other computer to make it run so bad? Could it all be in the tune? I just dont understand how the stock computer started it and ran it better with the +20s and 3 bar than the socketed smec. I remember reading that the injector board can go bad could that be my problem and is there any way to test it or is the only way to switch it out of my smec? Any input would be greatly appreciated. Thank you !

[cordes]

It would throw a code for the injectors if they weren't working. I would think that the cal would need to be very far out for the wrong map and injectors to run better with a different cal.

[ShelGame]

Are you sure about the MAP sensor being 3-bar? Did you check the voltage vs. pressure?

[minigts]

Are you sure about the MAP sensor being 3-bar? Did you check the voltage vs. pressure?

Yeah I didn't think a car would run correctly with a stock computer and 3bar MAP. Seems it would just the opposite or similar to what you were experiencing before.

[rgl10]

If you have access to a scanner check the coolant temp sensor and make sure its not reading 20 or more degrees colder than the motor actually is. If you don't have a scanner you can check it with a digital volt meter. You might want to check your fuel pressure and if you have an adjustable regulator try dropping the fuel pressure a few pounds and see if that helps. Also you said the cam timing was straight up. I take it that you mean the marks line up and not that the top hole is straight up. If it is at 12 o'clock then the cam is retarded at least one tooth or about 9 degrees which will lower idle vacuum and make it run rich. A plugged catalytic convertor will make it run rich and kill the power also. I guess there is no chance you have +40 injectors instead of +20's is there?

[turbors89]

I checked coolant temp sensor ohmed it out and it was reading correct also ordered my IAT sensor and wired that up. They are definately +20s ive had them in there for about two years now and it always ran great until a few months ago. Cam timing is lined up with the little top hole in the cover, with the other computer at idle its about 20/22 hg vac. I dont see how there can be a bad sensor or something if by switching out the computer the car ran geat but with the other it runs like garbage. I Cant see how the SIII tsmec cal can be that off to make it run like that though. Idk im puzzled lol.

[turbors89]

What tables should I adjust for cold start? I messed with the cold start enrichment curve a b and c but it doesnt seem to make a diffrence. How much should they be moved? Is there any other tables that need to be adjested? Starting off with a T-smec sIII tune.

[Turbo SOB]

What tables should I adjust for cold start?

I too am having difficulty with this. In addition to what's mentioned above I've played with "ColdLoadFromMAP" with very little benefit.

[ShelGame]

I too am having difficulty with this. In addition to what's mentioned above I've played with "ColdLoadFromMAP" with very little benefit.

Which cal?

[Turbo SOB]

I've been using "T-LM_25_MTX_CUST" as a base, with the injectors scaled to 42lb. I've tried it with and without the 3-bar MAP with no effect.

Here's how bad it's gotten:

[Turbo SOB]

I've really been taking a deep dive into this equation:

Start fuel uSec = [ STRTFL * STRTFL * (1 - STFBAR - STFTMP) * EPPMUL + (BATOFF * 4) ] * 4

Here's a quirk... In "T-LM_25_MTX_CUST" the X-axis under STRTFL (StartFuel FromTemp) is labeled as "Coolant Temp (in)", but in every other cal (even T-LM_25_ATX_CUST) it's labeled as "Temp (degrees)". The table STFTMP (FuelStartFuelFromCoolant) always has the X-axis labeled as "Temp (degrees)". Should I be assuming that STFTMP is referring to the coolant temp thermistor and STRTFL is referring to some other thermistor? Would this be the charge temp thermistor or something else (battery temp)?

In an effort to improve the situation I replaced the BATOFF table with the values from a SMEC BATOFF table. This reduced the pulse uSec by more than half, but I still get the black spot on the curb.

[Turbo SOB]

Hold the phone.....

I've done a quick comparison here. I took the results of the above equation and plotted it against EPP. Then, I scaled the cal to 42lb injectors and added that plot.



There seems to be a problem in how the injectors are scaled as it relates to the start fuel formula. As a result of the (1 - STFBAR - STFTMP) portion, the entire calculation prior to (BATOFF * 4) results in a negative number. The (BATOFF * 4) brings it back into positive territory. As a result, smaller values in the STRTFL table result in greater pulse widths.

Am I completely off base here? Did I misinterpret the equation from MPTune?

[ShelGame]

I'll have to look at it later. But, one thing to keep in mind when comparing LM cals to SMEC cals is that the timebase is different by a factor of 2, and not all of the tables are scaled the same. BATOFF for example.

[Turbo SOB]

timebade

????? Um. wut?

I'm assuming you mean fuel PW appears to be a factor of 2 but in real-time it is not. Somewhere something's getting multiplied by 2 to make up the difference?

Thanks.

BTW, I just tried a cal with EPPMUL scaled to cut the fuel in half, but it didn't make a difference. It's still making soot stains on the curb.