CUSTOMEFIS Multiport Idle issues

[djmac]

I have a CustomEFIS multiport setup in my truck with a dodge dakota T Body and I am having trouble with surging idle and poor starting. It used to start without touching the throttle at all and now I have to crack the throttle to get it to start and then give it a little throttle to continue running until it warms up or else it will stall. Once it does warm up the idle wanders and in general is to high. I should mention that I have a vacuum leak some where in that i only have about 15 pounds of vacuumn with a steady needle. I changed the intake gasket and checked all the vacuum lines and I dont have a break booster so I running out of places to look for the intake leak. I have already tried a new AIC valve and I changing out the tbody next week just to see what that does. Any other ideas as what is wrong?

[PlasticBoob]

I can't help you with your issue at the moment other than guessing it's probably the vacuum leak, oxygen sensor, or TPS, but may I ask you to please edit your title and put "CustomEFIS MPFI" in it? It'll make it easier for people to spot if they're just browsing through the forum pages looking for interesting threads in a few months.

Are you capable of datalogging? If so, can you post logs showing startup and idle?

[Dr.E]

Need more info

If it ran fine at one time then the vacuum leak is the most probable cause.
What if anything has been done since the problem started? Do you have any pictures of the system installed? Try the old propane bottle and hose trick to try to locate the vacuum leak source( do this in a well ventilated area and use caution to avoid any open flames or ignition sources) . The high idle is a classic vacuum leak symptom. Is this a speed density or MAF system?
Something simple like a hose to the MAP sensor may have been accidentally pulled off or developed a crack if this is a SD system.

[djmac]

I can't help you with your issue at the moment other than guessing it's probably the vacuum leak, oxygen sensor, or TPS, but may I ask you to please edit your title and put "CustomEFIS MPFI" in it? It'll make it easier for people to spot if they're just browsing through the forum pages looking for interesting threads in a few months.

Are you capable of datalogging? If so, can you post logs showing startup and idle?

I tried uploading a .uni file but I do not think this format is valid?

[djmac]

If it ran fine at one time then the vacuum leak is the most probable cause.
What if anything has been done since the problem started? Do you have any pictures of the system installed? Try the old propane bottle and hose trick to try to locate the vacuum leak source( do this in a well ventilated area and use caution to avoid any open flames or ignition sources) . The high idle is a classic vacuum leak symptom. Is this a speed density or MAF system?
Something simple like a hose to the MAP sensor may have been accidentally pulled off or developed a crack if this is a SD system.

Nothing has changed to cause the problem. I have tried propane,starting fluid etc to locate the leak with no result so I changed the intake anyway with no result. I have a map sensor which changed aswell as the hose to it. No change. I removed all the vacuum lines from the source, capped the source no change. I am currently removing the T Body from the adapter plate to change that gasket but I do not expect that to work either. Regarding the data log. I use Data Master to record logs. It uses .uni files which this site does appear to accept. Is there a work around?

[FSJ Guy]

If you can save it as a text file or a CSV (Comma Separated Value) file.

[PlasticBoob]

I use Data Master to record logs. It uses .uni files which this site does appear to accept. Is there a work around?

Or email it to me and I will host it for you. [email protected]

[Dr.E]

Sounds like others have had problems with this company.

http://www.northeastsurf.com/Custom%20EFIS%20Fuel%20Injection.htm

What ECM is used,ie. 1227730? What mask, ie. $8D? Describe the procedure you used to adjust the throttle plates and the IAC when you installed the new one? Do you have a DVOM? Have you checked the TPS? What are the IAC step counts that the datalog show at idle in gear? I know its a lot of questions, but it is hard to diagnose with out knowing as much info as possible.

[djmac]

Sounds like others have had problems with this company.

http://www.northeastsurf.com/Custom%20EFIS%20Fuel%20Injection.htm

What ECM is used,ie. 1227730? What mask, ie. $8D? Describe the procedure you used to adjust the throttle plates and the IAC when you installed the new one? Do you have a DVOM? Have you checked the TPS? What are the IAC step counts that the datalog show at idle in gear? I know its a lot of questions, but it is hard to diagnose with out knowing as much info as possible.

My experience with CustomEFIS was better than most. I think I purchased my system before he got overwhelmed. At any rate my system has worked very well for several years. I would like to answer all the questions but I have a few to ask so I can answer them.
Where do I find the ECM number? I know the ECM is from a 91 corvette. I have a flash burner so in the past I have recorded a data log and emailed it to the tuner.

What is a DVOM?

I have replace the AIC and TPS. I set the TPS to .56

Throttle settings: First I warmed the engine up then I disconnected the IAC. I reduced the rpm via the throttle plate screw to the lowest possible setting without stalling. Then i reconnected the IAC. Then I set the TPS to .56.
I will take a closer look at the IAC settings but I noticed after the idle settles down that the IAC is at 0 and so is the TPS Position? Does this sound right? One thing that has changed in the past is that in order to start the motor i have to give it some gas. It used to start just like factory efi just turn the key and go. Any suggestions on this symptom?

[FSJ Guy]

DVOM is Digital Voltage Ohm Meter.

[PlasticBoob]

DJMAC'S datalog: http://socalfsj.servebbs.net/storage...e052/djmac.uni

[djmac]

DVOM is Digital Voltage Ohm Meter.

Yes, I call it a multimeter. I have read where some have recommended keeping The iac counts at 40 and the Tps at 1;5% @ warm idle? How do you manipulate the settings to achieve that?

[FSJ Guy]

Yes, I call it a multimeter. I have read where some have recommended keeping The iac counts at 40 and the Tps at 1;5% @ warm idle? How do you manipulate the settings to achieve that?

That's usually for a TBI system. Bill over @ the Binder Planet advocates for this on a system that you are adapting to another engine. I don't know if this number is particularly correct for reprogrammed systems. I don't think it would translate to a MPFI system at all since the fuel is being injected downstream of the throttle plates (at the valve) versus on top of the throttle plates on a TBI system.

The TPS should be set for whatever your system calls for. TBI systems want to see about 0.57 volts (IIRC) for a closed throttle position.

I don't know how your throttle plates are adjusted, but I suspect there's a screw adjustment somewhere on the throttle body.

[djmac]

.57 is what I recall setting it to in the past. What I am unclearon is what a good starting point for t plate opening? That maybe why I have to push the pedal a littleto get it to start? Or maybe the iac is at the wrong position at the time of start?

[FSJ Guy]

This link shows what ECM you might have. Scroll down to the bottom.

http://tpiparts.net/ecms_and_proms/

Look over @ the Third Gen forums and see if you can finds ome tech info about what your throttle plates and IAC should be set at.