Discussion
Hi folks,
My car is predictably running badly again, will probably need to get the TBs refurbed at some point because throttle balance doesnt hold on for more than 600 miles or so.
This is complicated for a noob like me to explain, there are a few things going on which may or may not be related, I hope I make sense.
So, recently I pooped my pants because I received a low oil pressure warning when coming to a stop at lights, after a fun run to heat up the car to dry out the fuse board... there is rain/humidity getting in from somewhere and landing on the fuse board, causing the dash not to turn off, alarm going randomly, etc.... I know this for certain because there was green/copper oxidation drip mark under one of the relays!
The low pressure was caused by revs drooping to around 630rpm intermitently, only sometimes not always. I am now manually holding revs up at 1000 rpm to try and keep it sweet, but when it happens it can be difficult to stabilise because you can start to do a see sawing dance with it.
Anyhow, I got my diagnostic cable and computer out for the first time, turned the car On and saw right away tpot2 very unstable going up and down to 30% whereas tpot1 was stable at 14.8, it returned to normal after a few seconds pumping the throttle. Started the car cold, daptives were unstable, hitting 30 at times and there was a bad afr fault on 456.
From then on logged every trip to try and get a better understanding of it. The next time I started the car cold it was tottaly fine apart from usual lowrevs, no crazy tpot2 readings, but later when I got it hot it started doing it again when coming to a stop at lights.
What I think I understand from this is that tpot2 is intermitently having a fit at idle (only at idle), it spikes to 55%, while tpot1 sitting happy and stable at around 15. I guess this is flooding 456, causing bad afr which in turn causes the drop in revs, right?
I bought tpots and leads (along with other service bits) from tvr power.
Should I replace tpot2 and do the pot reset procedure? Is this hard to do? Is there a guide thread for the spannering?
I'm also planning to turn the idle screw when hot as a temporary measure until the garage has availabilty to do the balance.
I would very much apreciate any advice on this.
I can pm the actual log if any of you kind educated people want to analyse it.
My car is predictably running badly again, will probably need to get the TBs refurbed at some point because throttle balance doesnt hold on for more than 600 miles or so.
This is complicated for a noob like me to explain, there are a few things going on which may or may not be related, I hope I make sense.
So, recently I pooped my pants because I received a low oil pressure warning when coming to a stop at lights, after a fun run to heat up the car to dry out the fuse board... there is rain/humidity getting in from somewhere and landing on the fuse board, causing the dash not to turn off, alarm going randomly, etc.... I know this for certain because there was green/copper oxidation drip mark under one of the relays!
The low pressure was caused by revs drooping to around 630rpm intermitently, only sometimes not always. I am now manually holding revs up at 1000 rpm to try and keep it sweet, but when it happens it can be difficult to stabilise because you can start to do a see sawing dance with it.
Anyhow, I got my diagnostic cable and computer out for the first time, turned the car On and saw right away tpot2 very unstable going up and down to 30% whereas tpot1 was stable at 14.8, it returned to normal after a few seconds pumping the throttle. Started the car cold, daptives were unstable, hitting 30 at times and there was a bad afr fault on 456.
From then on logged every trip to try and get a better understanding of it. The next time I started the car cold it was tottaly fine apart from usual lowrevs, no crazy tpot2 readings, but later when I got it hot it started doing it again when coming to a stop at lights.
What I think I understand from this is that tpot2 is intermitently having a fit at idle (only at idle), it spikes to 55%, while tpot1 sitting happy and stable at around 15. I guess this is flooding 456, causing bad afr which in turn causes the drop in revs, right?
I bought tpots and leads (along with other service bits) from tvr power.
Should I replace tpot2 and do the pot reset procedure? Is this hard to do? Is there a guide thread for the spannering?
I'm also planning to turn the idle screw when hot as a temporary measure until the garage has availabilty to do the balance.
I would very much apreciate any advice on this.
I can pm the actual log if any of you kind educated people want to analyse it.
SergSC,
I will let you know how I get on with my refurbished throttle body's but it's now been 4 weeks since I dropped them of and no sign of them, so it might be worth rebalancing them every 600 or so miles during the summer and using the car while the weather is good. My car has not turned a wheel in 7 weeks and I am away on holiday next week for 2 weeks, hopefully they will be waiting on me when I get back.
George
I will let you know how I get on with my refurbished throttle body's but it's now been 4 weeks since I dropped them of and no sign of them, so it might be worth rebalancing them every 600 or so miles during the summer and using the car while the weather is good. My car has not turned a wheel in 7 weeks and I am away on holiday next week for 2 weeks, hopefully they will be waiting on me when I get back.
George
natben said:
SergSC,
I will let you know how I get on with my refurbished throttle body's but it's now been 4 weeks since I dropped them of and no sign of them, so it might be worth rebalancing them every 600 or so miles during the summer and using the car while the weather is good. My car has not turned a wheel in 7 weeks and I am away on holiday next week for 2 weeks, hopefully they will be waiting on me when I get back.
George
Hope you get that back soon.I will let you know how I get on with my refurbished throttle body's but it's now been 4 weeks since I dropped them of and no sign of them, so it might be worth rebalancing them every 600 or so miles during the summer and using the car while the weather is good. My car has not turned a wheel in 7 weeks and I am away on holiday next week for 2 weeks, hopefully they will be waiting on me when I get back.
George
I wonder how PetroHeadPetes inovative solution is keeping up. And if he wants to do mine next
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
SergSC said:
I wonder how PetroHeadPetes inovative solution is keeping up. And if he wants to do mine next
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
PetrolHeadPete writes as a résumé:http://www.pistonheads.com/gassing/topic.asp?h=0&a...
"I can still report the "usual" lumpiness at light throttle / load at between 2000 and 2500. Almost like a misfire. That's been there since I bought the car btw and despite all these mods and various engine tweaks, its still there. Now the low speed side is fixed i'll have a think on this other issue.
"
So i wouldn't pay that much attention to the bodies apart of correctly balancing them. There seems to be many other things involved to a smooth running.
I dont have that 2000-2500 rpm hesitation problem. From what I have been reading on all tb threads on here, that particular issue appears to have many possible and sometimes apparently simultaneous causes, so I wouldnt discount it just because he still has that.
Petes idea seems intuitively sound, tpot in the middle and remove slop in the system, at least in terms of the delay between throttle input and response at the outer cylinders. I would have thought this would help loads with the tendency to fall out of ballance. The stiffeners alone seem like a very good idea.
Then again we havent heard from the real experts about it so...
What I think is happening in mine is that slop in the system causes rough idle running, which causes even more wear and so on, in an ever tightening hopeless spiral of throttle body doom...
Petes idea seems intuitively sound, tpot in the middle and remove slop in the system, at least in terms of the delay between throttle input and response at the outer cylinders. I would have thought this would help loads with the tendency to fall out of ballance. The stiffeners alone seem like a very good idea.
Then again we havent heard from the real experts about it so...
What I think is happening in mine is that slop in the system causes rough idle running, which causes even more wear and so on, in an ever tightening hopeless spiral of throttle body doom...
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