Youngs92

iTrader: (1)

I recently replaced my ECM with a used one from an automatic with the same engine code, but have been noticing some strange behavior. The car likes to idle between 6 and 700 RPM, and on take off, if the revs drop to 400 or lower, the car goes into a high idle mode so it's nearly impossible to stall. It sits around 1200 RPM and will not come down until I shut it off and turn the car back on. Is there any difference between an auto computer and a manual one? Any other suggestions are welcome.

vetteoz

iTrader: (13)

No

It is the memcal ( chip ) fitted inside the ECM that determines what the tune is for.
You are supposed to fit your original memcal ( blue item shown below ) into the replacement ECM

Youngs92

iTrader: (1)

The car was a tbi and was converted by the previous owner to TPI except for the computer. Can I use the memcal from the tbi computer or do I need to purchase one for my current setup?

Six_Shooter

iTrader: (2)

The TBI PROM will be very different than the TPI MEMCAL, both in physical fitment and calibration.

You need to get a proper MEMCAL for your application.

Youngs92

iTrader: (1)

Are prom and memcal different things? Any recommendations as to where to get one? I know nothing about these computers so I appreciate the help

vetteoz

iTrader: (13)

https://www.thirdgen.org/forums/post...781-post4.html

Not sure how , you need a TPI computer
See
https://www.thirdgen.org/tbitotpi

What is the service # on the computer you are now using ?
The 1227165 shown on the ECM in the pic above

gt4373

This Site Might Help.

http://www.iroczone.com/2009/10/ecmm...oss-reference/

Youngs92

iTrader: (1)

I will look up the number tonight. I know you were supposed to swap the computer but the owner didn't, so it ran like garbage for years. Thanks for the help I'll get back to everyone tonight

Lucid

iTrader: (4)

The PROM contains the programming required for your setup to run properly and is a chip that is on the MEMCAL. The MEMCAL has resistors on it in case there is a failure and you need to run in limp home mode to drive it somewhere.

You need to get the right ECM and right MEMCAL for your application and type of TPI. There is a Mass Air Flow (MAF) and Speed Density (SD) version of Tuned Port Injection and they require different ECMs and MEMCALs.

A 1227165 ECM will get you started* if your TPI is from an 86-89 MAF setup. Go look and see if you have a MAF sensor on your car. It is cylindrical in shape and will be between the air filter and throttle body with wires going to it and have its own connector. A SD setup will be missing this sensor and have ducting going from the air filter to the throttle body or be missing the ducting and have the air filter directly connected to the throttle body. If you suspect you have an SD card, go hunting for the Manifold Absolute Pressure (MAP) sensor.

*An exception to this is the 1985 MAF TPI system, the ECM was different for that year (1226870) ECM. I've only ever seen one car with that system, so hopefully its one of the common ones.

Youngs92

iTrader: (1)

Thanks for the explanation. The car is MAF and the current computer is 1227165. There is a string of letters and numbers under that number (868461 M713125595) and above the barcode (16068461) if these mean anything to anyone. The computer is the same setup as my 92 TBI was, two black connectors at the bottom and the chip is blue but I couldn't see any letters or numbers on it

vetteoz

iTrader: (13)

'165 ECM is correct ECM for a MAF engine

Need to identify the memcal , could be wrong for your combo

Look for a 4 letter code , something like ARAP on the silver disk

Youngs92

iTrader: (1)

It says ABYA next to the '165 number, is that the chip code?

vetteoz

iTrader: (13)

That is what memcal ( '88350 auto ) was originally fitted at the factory.
More important is what memcal is in it now ?

Youngs92

iTrader: (1)

I will check tomorrow the code in the MEMCAL itself but I don't think it was ever altered

Youngs92

iTrader: (1)

I haven't been able to check the number yet but can anyone tell me why the automatic prom would not allow a manual car to run properly?

OrangeBird

iTrader: (1)

Sure can , The automatic chip is looking for things it's not seeing ( like the "PRND321" switch , for ex. ) and is seeing things it's not expecting to see ( like the clutch switch , for ex. ) . These conflicts in the info provided VS the expected signals are "messin with it's mind" and producing the odd running your experiencing .

Lucid

iTrader: (4)

We need some more information about the car to really help you with this. Is it a 305 engine or 350 engine? What year is the car originally?

The Vehicle Speed Sensor might be different depending on the year. You probably need to adjust the TPS sensor in any event. IIRC, early TPS sensors are adjustable and late model TPS sensors are fixed. You may need to adjust the TPS to fix your tip in and high idle. There are also probably different settings in the T5 proms that smooth the idle when you push the clutch in and transition gears.

If you want to get into chip burning, you could buy a Moates Adapter (so you can put your own chip in the memcal), flashable chip and a burn2 and make your own adjustments to the program like enabling the 5 speed flag, disable the Torque Converter TCC stuff or start off with the 305 TPI T5 programs (BINS) flash it, and run it to see how much difference there is.

You could also look for a MEMCAL out of an 87-89 305 TPI with a 5 speed.

Some examples of flashable BINS:
http://www.eecis.udel.edu/~davis/z28/index.html

Youngs92

iTrader: (1)

Thanks for the info guys. The car was originally a 92 305 TBI manual. I just did the TPS, but I do need to set the proper engine timing. I'm currently using a GPS VSS unit from Dakota Digital and I have 2k pulses dedicated to the ECM which I believe is correct for the 88 computer. I'm not adventurous enough to burn my own chip and I don't want a used one just in case it's bad, so I will certainly look into getting a programmed chip from somewhere

OrangeBird

iTrader: (1)

There is a guy named Brian who has a company called "tunedperformance" (hope I spelled that right) who is a member here and everyone reports great results with his work on programming chips for our cars . You may want to PM him and see what he can do for ya ?

vetteoz

iTrader: (13)

I linked him in post # 6

Only cuts out the starter; has no connection to the ECM

OrangeBird

iTrader: (1)

[quote=vetteoz;5765139]I linked him in post # 6

Didn't notice cause you didn't directly mention the name "tunedperformance" , and I didn't follow your link ......


Only cuts out the starter; has no connection to the ECM

Your right about it not directly connecting to the ECM , but it doesn't only cut out the starter . If you look at the cruise control schematic* , the clutch does in fact have a switch that connects to the cruise module (which then itself connects to the ECM) .

At any rate , I'm sure Brian will get it done , if the OP decides to go that route ...


* The schematic I reference was from austinthirdgen.org .

vetteoz

iTrader: (13)

But it does not input to the ECM; CC gets speed signal from ECM

The only ECM input relevant is the P/N indication switch on the auto cars so the ECM adjusts the idle speed when going into /or out of gear

Youngs92

iTrader: (1)

Thanks everyone, that may explain why the idle is so unsettled. I'll contact him and be back running soon!