4ltr ECU in a 5ltr
Discussion
Can someone tell me if there will be a problem putting the ECU from a 4ltr car into my 5ltr ?
I want to see if this improves the MPG issues I have been having.
Would it do any damage to my 5ltr ?
Ideally I would swap the chip round at the same time as part of the test, but don't yet know if this is in a socket fit or soldered in directly to the ECU.
I want to see if this improves the MPG issues I have been having.
Would it do any damage to my 5ltr ?
Ideally I would swap the chip round at the same time as part of the test, but don't yet know if this is in a socket fit or soldered in directly to the ECU.
Unless you are doing high mileage I do not believe that the costs of what you are considering would ever be recovered by any significant fuel savings.
You might do better buying a reliable old banger for every day use and thereby reducing considerably the cost of ownership of the TVR. Less fuel, less service costs, less insurance on classic restricted mileage policy, less servicing, higher TVR residuals from lower mileage etc.
You might do better buying a reliable old banger for every day use and thereby reducing considerably the cost of ownership of the TVR. Less fuel, less service costs, less insurance on classic restricted mileage policy, less servicing, higher TVR residuals from lower mileage etc.
PeterC said:Indeed, although you do have to factor in double the MOT and road tax, plus the cost of insurance and servicing on the runabout. Sometimes it makes sense, other times it doesn't.
Unless you are doing high mileage I do not believe that the costs of what you are considering would ever be recovered by any significant fuel savings.
You might do better buying a reliable old banger for every day use and thereby reducing considerably the cost of ownership of the TVR. Less fuel, less service costs, less insurance on classic restricted mileage policy, less servicing, higher TVR residuals from lower mileage etc.
When you get to 4+ cars, it feels like you're always either taxing, insuring, MOTing, servicing or repairing one of them!
PeterC,
this was just a further test to try to identify what has caused the drop in MPG (having changed/checked just about everything else).
I know someone with a 4ltr Chim that would lend me their ECU for test purposes.
it is not planned to be a long term swap, just a test to see if a different ECU (and/or chip) makes a difference.
It seemed to solve a lot of andy-w's problems and I thought it would be worth a test.
Unfortunately nobody on the recent Surrey Rolloing Road day offered to lend me theirs....as that would have been a pretty thorough test.
>> Edited by philr on Tuesday 22 November 14:19
this was just a further test to try to identify what has caused the drop in MPG (having changed/checked just about everything else).
I know someone with a 4ltr Chim that would lend me their ECU for test purposes.
it is not planned to be a long term swap, just a test to see if a different ECU (and/or chip) makes a difference.
It seemed to solve a lot of andy-w's problems and I thought it would be worth a test.
Unfortunately nobody on the recent Surrey Rolloing Road day offered to lend me theirs....as that would have been a pretty thorough test.
>> Edited by philr on Tuesday 22 November 14:19
My understanding is that both the ECU and programming (unless modified) are idential between the 4 and 5's ECUs. Its the value of the tune resistor that tells the ECU which map to use.. It may well be worth checking another ECU to eliminate it but it won't matter if it a 4 or 5..
Besides you really don't want to be running a 5 of fuel for a 4 this would be really lean.. causing misfires, very high cylinder temps.. etc that wouldn't be good..
SSR should have printed you a AFR/power graph what does this say?? is it running rich? or is it just costing a lot to run??
if it is running rich then it could be running in limp home check CLT sensor and lambdas they would be my guess, what have you checked already?? I second JonRB if you want to be sure its running properly take it to MA hes one of the few who could tell you, and adjust it to your requirements..
chris
Besides you really don't want to be running a 5 of fuel for a 4 this would be really lean.. causing misfires, very high cylinder temps.. etc that wouldn't be good..
SSR should have printed you a AFR/power graph what does this say?? is it running rich? or is it just costing a lot to run??
if it is running rich then it could be running in limp home check CLT sensor and lambdas they would be my guess, what have you checked already?? I second JonRB if you want to be sure its running properly take it to MA hes one of the few who could tell you, and adjust it to your requirements..
chris
griffsmith,
I'm not clear from your note whether you think putting a 4ltr ECU into my 5ltr will be a problem or not. You suggested that the tune resistor would dictate which fuel mapping was used.
You are right that I don't want to be running the engine too lean if that is what a 4 ltr mapping would do for me.
The SRR graphs showed the air/fuel mix as being very rich.
Power and performance is still good. 266 bhp (fly wheel presumably) and 300+ torque.
So far I have changed the Lambdas, AFM (2nd hand unit from ACT/Austec but known to be OK), Coolant temp sensor + had the injectors checked and cleaned (££££
.
I have checked and cleaned the plugs + all connections. Plugs were very sooted up.
I have done several long runs to try to blast away any cobwebs.
I'm not particularly heavy footed, but since the problem started (18 months + ago) I tend to get more like 14 to 15 MPG on the run to work and 20 on a long run.
I was down to 12 to 13 MPG until recently, but the injection guys spotted a vacuum pipe to the plenum was split and that seemed to improver things a little.
Note that I used to get 17 to 18 MPG on a run to work and 23 to 24 on long runs, so things have definitely dropped for some reason.
15 MPG is more bareable than the 12 that I was getting though.
Needless to say that the current cold weather isn't helping things.
I'm not clear from your note whether you think putting a 4ltr ECU into my 5ltr will be a problem or not. You suggested that the tune resistor would dictate which fuel mapping was used.
You are right that I don't want to be running the engine too lean if that is what a 4 ltr mapping would do for me.
The SRR graphs showed the air/fuel mix as being very rich.
Power and performance is still good. 266 bhp (fly wheel presumably) and 300+ torque.
So far I have changed the Lambdas, AFM (2nd hand unit from ACT/Austec but known to be OK), Coolant temp sensor + had the injectors checked and cleaned (££££
. I have checked and cleaned the plugs + all connections. Plugs were very sooted up.
I have done several long runs to try to blast away any cobwebs.
I'm not particularly heavy footed, but since the problem started (18 months + ago) I tend to get more like 14 to 15 MPG on the run to work and 20 on a long run.
I was down to 12 to 13 MPG until recently, but the injection guys spotted a vacuum pipe to the plenum was split and that seemed to improver things a little.
Note that I used to get 17 to 18 MPG on a run to work and 23 to 24 on long runs, so things have definitely dropped for some reason.
15 MPG is more bareable than the 12 that I was getting though.
Needless to say that the current cold weather isn't helping things.
You might find some helpful info on this thread:
www.pistonheads.com/gassing/topic.asp?t=223687&f=13&h=0
If your car is only doing 13-15MPG, then there really is something wrong with it!
www.pistonheads.com/gassing/topic.asp?t=223687&f=13&h=0
If your car is only doing 13-15MPG, then there really is something wrong with it!
Well I certainly have a resistor in place ....white wires , so it sounds like this is the correct one for the 5ltr.
As far as I can trace the resistor wires back (they disapearinto the the wiring loom up behind the dash somewhere) it seems to be connected.
Unlike the photo in the other thread I don't have the blue connectors visible (if they are there even).
Maybe I need to get Mark to take a look at the setup for me after all.
As far as I can trace the resistor wires back (they disapearinto the the wiring loom up behind the dash somewhere) it seems to be connected.
Unlike the photo in the other thread I don't have the blue connectors visible (if they are there even).
Maybe I need to get Mark to take a look at the setup for me after all.
philr said:
griffsmith,
I'm not clear from your note whether you think putting a 4ltr ECU into my 5ltr will be a problem or not. You suggested that the tune resistor would dictate which fuel mapping was used.
Sorry yeah it wasn't too clear.. although I think your sorted now..
philr said:
The SRR graphs showed the air/fuel mix as being very rich.
Power and performance is still good. 266 bhp (fly wheel presumably) and 300+ torque.
Out of interest what were the AFR values through the rev range?
Mark,
Like you said 12-15 MPG is not right for a 5ltr.
Can you tell me if ECUs go wrong very often ?
I know what the car used to deliver in the the way of MPG, and there was a marked drop about 18 months ago.
Is this something that would be "easy" to diagnose by yourself if I were to bring the car to you (at Austec) ?
I guess my concern would be whether we could identify the actual root cause of the problem rather than just remapping the ECU, which migth just mask an underlying problem.
Cheers
Phil
Like you said 12-15 MPG is not right for a 5ltr.
Can you tell me if ECUs go wrong very often ?
I know what the car used to deliver in the the way of MPG, and there was a marked drop about 18 months ago.
Is this something that would be "easy" to diagnose by yourself if I were to bring the car to you (at Austec) ?
I guess my concern would be whether we could identify the actual root cause of the problem rather than just remapping the ECU, which migth just mask an underlying problem.
Cheers
Phil
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