rcajun86

Just changed from a Super Ram to a Mini Ram car starts and runs good when you start to give it gas it stumbles until it get some rpm's up. At idle and try to give it gas it pops thru the throttle body somewhat until the rpm's get up. Would it be the Throttle Position sensor or the idle air control sensor or something else ? Wide open throttle the motor pulls really hard busting the tires loose and getting the car sideways.
thanks for any suggestions

vader86

First question is what is the TPS voltage reading, and what are the IAC counts?

bjankuski

More then likely you need a tune change, the mini ram requires much more acceleration fuel then the superram. The pop and stumble are a sign that the car is lean on throttle roll on and could use more fuel.

DanielRicany

I agree with bjankuski. You need to have a tune done to add more acceleration enrichment.

JackDidley

The Mini likes more fuel and mine also likes more advance in the tune. Turn the distributor a few degrees and if it helps, tweak the advance in the tune.

rcajun86

Vader
I have not checked the TPS readings yet not sure what they should be since the motor is a 383 or does it matter. Will have to look up what the voltage should be it been awhile since i set the TPS .
Now the IAC counts i do not know anything about please explain.
Thanks

rcajun86

I was wondering if a new tune would be the answer.

DanielRicany

Okay so now we're finding out more... It's a 383. Does it have a different cam than the original? What else is changed? Different or ported heads? Was it previously tuned for the Super Ram set up?

vader86

Ok so that makes me think very little has been checked with your tune since this switch, so what they are saying above is likely the culprit. Your chip must be reprogrammed, and that will discover the real problem. Looking at TPS, the base throttle screw setting, and IAC will only point to it. These can only be read with a scanner or software/laptop with cable.

TPS is the sensor on the TB passenger side that tells the Computer where the throttle is set. It should be 0.54 V. Engine size doesn't matter.

IAC counts show how hard the IAC is working to keep the thing running, and should be low. My bet is that yours are very high.

GREGGPENN

In case a few explanations help this all to make sense....

I agree there's need for a tune. Technically speaking, short-runner intakes (e.g., miniram) can provide air more quickly on tip-in than long-runner intakes. That's because it's easier to move their shorter "columns" of air into the chambers.

The TPS (throttle position sensor) tells the computer where the linkage is sitting as any given point -- which directly translates to a percentage throttle opening. (As stated .54V is your minimum setting for idle.) As the throttle opens, TPS voltage increases.

The IAC is a motor/air passage combo that feeds additional air "around" the throttle blades. Higher counts mean the stepper motor (that opens this passage-way) is letting more air to supplement what's going through the throttle blades.

Primarily, the IAC replaces the dashpot formerly found in a carburetor. The IAC slowly graduates the closing of air/fuel when slowing down. Acceleration "tip-in" used to be performed by a small "accelerator pump" in a carburetor. Now, the computer can take care of "tip-in" by telling the injectors to squirt more fuel.

In short, the computer (ECM) feeds the correct amount of fuel necessary to hit target air-fuel ratios for any given load/rpm/temp/etc... As long as the ECM "knows" how much air is getting in, the injectors can respond correctly. Changes in the ability to feed/pull air -- like changing intakes -- can actually alter how MUCH air is going through the throttle blades and into the motor.

Of course, temperature/density make a difference in air (AFR) too. That's why more that one/two sensors are required to electronically control a motor.




FWIW: I think a couple of posters in this thread are engineers and probably could have stated my points in simpler terms.

rcajun86

Ok guys i guess i should have filled everyone in on the motor sorry for not doing that. It's an 088 block 383 , 6" promod rods , keith black forged pistons,a good steel crank, the new AFR 195 heads, hooker headers, lingenfelter 74219 cam all msd distributor and external coil. Had the Super Ram on it and it had been tuned by Corey Henderson which was a little distance to haul my car to him since i'm in the Dallas Fort Worth area, o yes it has a beefed up 700r4 with a 2600 stall. I'm believing that everyone on here is correct in saying it needs another tune wish i could find someone close to the Dallas Fort Worth area to tune it don't really won't to drag it that far again. guys i do appreciate all the advice and help. if someone knows of a good tuner close by i'd certainly appreciate their names.
Thanks again

DanielRicany

My bet is that you can probably get away with an email order tune on this one. Really the only thing that may need to be corrected is the MAF tables and acceleration enrichment. If you're lucky, your WOT AFR did not change by much. I would go with an AFR gauge if I was in your shoes and contact someone who can do email tunes for your car. This way you don't have to go so far.