Noob upgrading the ECU on a 1994 855T

azureblue · Post by **azureblue** » 26 Dec 2009, 15:39

I have a 1994 855t, bought second hand with a replacement engine,. I recently got a T5R ECU to drop into to it, to get a little more HP from the engine. The new ECU went in great, works fine, except for making the trip computer's MPG calculator a little erratic. The car has more mid range kick and the shifts are smoother, maybe at the loss of a MPG or two. I put it in in the middle of some snowy weather, so I have not had time yet to R&R the spark plugs and air filter, and check the hoses for tightness, but that should come tomorrow.

I did some research ad here is what I had in the car. Apparently, it seems to be a 96 ECU- it made the car "snarl" for lack of a better description, and seemed to have a bit of turbo lag. The reference chart also tagged this as a T5 ECU, but I can't say for sure. But here are the numbers for it:
BOSCH 0 261 203 072
8.2
p06842210 cp04
1t26s3149 t93481263

the one I bought (supposed to be a T5R, and I don't doubt the seller) has these numbers:
BOSCH 0 261 203 628
7.2
p01271240 c001
1t2Xs4008 t96051027 (the x is an unreadable number).

If this makes any sense.

Could somebody who knows these things fill me in on what I had and what I bought? Tips, advice, etc.?

Thanks

z31jaime · Post by **z31jaime** » 24 Jan 2010, 01:07

ok what you had....ending in 072 is the OEM "turbo" ecu. the 628 is the "r" ecu. being that its a 96+ you also got rid of your EGR code (make sure it is all sealed up or u will have an unknown vac leak from it and wont get CEL cause the 96+ is non egr)

the only real difference with them is a few HP gaind by higher psi...i think the 072 is 8.1psi and the 628 is 9.2psi or something like that (dont remember off the top of my head) the reason everything is acting all crazy is because the ECU requires some time to adapt to all the issues of the car. it requires "duty cycles" to be completed before everything starts to act normal. i swap my ECU alot (i have a Inmotion tuned 1995 072 ecu) and i have an OEM 96+ 072 ecu. the inmotion trips my EGR system (cause its bad) so for daily driving i use my 96+ if im planning on going to the races or a show i drop the Inmotion a few days before and let it reset itself...sometimes it can take a few hundred miles before the ECu "resets" and starts acting normal.

azureblue · Post by **azureblue** » 24 Jan 2010, 10:12

thanks- this explains quite a bit. How do I get rid of the EGR code? Do I have to remove something from the engine? (This is a non California car) Should I pull the battery negative and let the car reset?

The car is running a little rich- the plugs are mildly sooty - not fouled, the electrode is clean, but fluffy carbon on plug. Given a new air filter and everything else stock, does this mean the O2 sensor acting up?

Also, I am trying to find the right plugs, and it seems that there is a toss up between NGK coppers, Bosch Super coppers, and OEM plats. Your preference? I found that Autolite coppers don't work too well, and Autolite single electrode plats are sort of OK.

z31jaime · Post by **z31jaime** » 26 Jan 2010, 10:55

if you put in the 96+ R ecu you should have to do nothing to the EGR system. it will not throw a CEL for EGR because the ECU is not made with the EGR sencor..get it? if you swap and still get a CEl code i would have it checked...if you get EGR again then its not a 96+ ecu and your egr system needs to be repaired.

i doubt the O2 is acting up. my wagon starts to run rich after the plugs have been in for a while even if they are not fouled....i would replace your spark plugs and see how that changes the car.... AND MAKE SURE YOU GAP THEM CORRECTLY. that made all the difference in the world in my 850's. if i just opened the box and shoved them in i would run rich, but i would gap them correctly and the car rean really clean.

i haverun the OEM in my NA and they have lasted much longer than any other set i have gotten (almost a year now).... in my turbo wagon...i ran NGK iridums for about 3 months and then they started to foul out. autolite plat. for about 2 months, bosch for about 3 weeks, and denso plats. for the last 4 months. i have never put copper plugs because my local autozone never has any in stock. i did my plugs last weekend and they happen to have splitfire coppers, for my car....not the best but they seemed to clean up the exhaust smell very well.