PROBLEM 3.5-4.6 w/ motec

[tbjaus2000]

Wondering if someone can help me. My dad has an 88 3.5l RR. We ditched the engine and had a 4.6L engine put in, It was a second hand block, tested, re sleeved. Heads were recod as well. Ran ok on original computer setup. We since, have installed a motec the older type. We have, however, we have installed an air flow meter for the motec while retaining the air temp sensor for the original lucas. Thus, we have wired both ecus and are able to use the orig lucas as a spare.
2 PROBLEMS

1. It has a bucking problem on deceleration, which has almost all been tunned out.
2. It has a heap of flat spots. 2-3k is use less, above 3k look out!

Has anyone done a similar conversion, or possible know what may cause this. Mechanic that did all the work is struggling as well. Thanks for the help.

[stuee]

Your best to take it to a speed shop that actually deals with motec and tunes them regularly. If you find one they should also know if all the sensors are compatiable etc. Its best to if they have a dyno so they can give you a good tune. Dyno sessions can range from about $700 up but once tuned properly you should only have to worry about servicing it. Since it sounds like you've got a base map sorted it shouldn't take to long to tune it.

Why did you install a air flow meter? I always thought motec have been compatable with either TPS's or MAP sensors. Less airflow restriction and sometimes better response.

[rohan canavan]

which motec are you running ,are you running as a piggy back system
if so why?

[justinC]

Are you in Victoria?
Vitesse developments have vast experience with the early Motec systems for RR's, that was all they used to use. The system I'm talking about was fuelling only, and had an array of trimpots for 500rpm intervals once the lid was off. Had a MAP sensor tube and air temp sensor also.
I had a customer who had his Vitesse Rangie dynoed, it never ran properly after that.
I ended up sending unit to Melb for vitesse to reload original spec map and since then perfect. The first thing they asked me was " Has the vehicle been near a dyno?"
They Know these systems and it was a cheap fix too.

[kurmit]

Wondering if someone can help me. My dad has an 88 3.5l RR. We ditched the engine and had a 4.6L engine put in, It was a second hand block, tested, re sleeved. Heads were recod as well. Ran ok on original computer setup. We since, have installed a motec the older type. We have, however, we have installed an air flow meter for the motec while retaining the air temp sensor for the original lucas. Thus, we have wired both ecus and are able to use the orig lucas as a spare.
2 PROBLEMS

1. It has a bucking problem on deceleration, which has almost all been tunned out.
2. It has a heap of flat spots. 2-3k is use less, above 3k look out!

Has anyone done a similar conversion, or possible know what may cause this. Mechanic that did all the work is struggling as well. Thanks for the help.

Adrian from rangie give me a call we do alot of tuning on after market computors give me a call and ill see if i can fix the problem for you
97396989