Air Mass Meter. Adjusting Screw?

[ntel]

In an attempt to diagnose a slight over fuelling problem I have with the Chim 450, I have swapped my air mass meter for a similar one from my neighbours 4.2L Range Rover. Having covered about 400 miles with the RR unit on the car I am now getting about 21mpg as opposed to 18mpg and the car feels much torquier. I noticed, what appears to be, an exposed adjusting screw on the unit from my car. The unit from the RR has a metal seal over its adjusting screw. Would it be fair to assume, that sometime in the past, the seal has been removed and the meter has been adjusted in some way or other or are all TVR air mass meters like that? Does anybody know if the unit can be adjusted to give correct operation?

[GreenV8S]

If it can be adjusted, I'm sure it can be adjusted to give incorrect operation, going the other way may not be so easy!

[ntel]

GreenV8S said:

If it can be adjusted, I'm sure it can be adjusted to give incorrect operation, going the other way may not be so easy!

Yes, fair enough. My AMM is clearly not right, but rather than splashing out on a new one I'd rather try to re-adjust it first if at all possible.

[mongoose]

hi dave,it does sound like someones made an adjustment in the past.this is what the chaps at v8 developments did to mine to adjust the fuelling after modifying.if you click on the link below,you get the rpi website,which tells you how to set up the amm.as long as you measure the voltage first,then you can always return to where you are presently if all else fails,so why not give it a try-i would!heres the link www.rpiv8.com/carbs-2.htm#setting-up take a look under the section titled 'setting air mass/flow meter&throttle pot'-good luck,mike.

[ntel]

mongoose said:

hi dave,it does sound like someones made an adjustment in the past.this is what the chaps at v8 developments did to mine to adjust the fuelling after modifying.if you click on the link below,you get the rpi website,which tells you how to set up the amm.as long as you measure the voltage first,then you can always return to where you are presently if all else fails,so why not give it a try-i would!heres the link www.rpiv8.com/carbs-2.htm#setting-up take a look under the section titled 'setting air mass/flow meter&throttle pot'-good luck,mike.

Bloody ell Mike! What a great link. Thanks for that. I have a fancy Kane and May combustion meter for checking industrial boiler emmissions, I think I can set it up for reading different fuels. Thats my job for Saturday then!

Thanks again

Dave

[HarryW]

ntel said:

mongoose said: hi dave,it does sound like someones made an adjustment in the past.this is what the chaps at v8 developments did to mine to adjust the fuelling after modifying.if you click on the link below,you get the rpi website,which tells you how to set up the amm.as long as you measure the voltage first,then you can always return to where you are presently if all else fails,so why not give it a try-i would!heres the link <a href="www.rpiv8.com/carbs-2.htm#setting-up">www.rpiv8.com/carbs-2.htm#setting-up</a> take a look under the section titled 'setting air mass/flow meter&throttle pot'-good luck,mike. Bloody ell Mike! What a great link. Thanks for that. I have a fancy Kane and May combustion meter for checking industrial boiler emmissions, I think I can set it up for reading different fuels. Thats my job for Saturday then! Thanks again Dave

Whilst you're there on the throttle pot bit, after you've checked that you have the 0.34V zero throttle reading. Check you can get at least 4.6V with full throttle, do this using the loud peddle so you can be sure the linkage and butterfly are fully open, also view the butterfly to ensure too. You'd be surprised how many cars never reach proper full throttle. Good idea if you've had to adjust any of these settings to reset the ECU before running.
All IMHO etc.

Harry

[ntel]

OK chaps. I've reset the AMM and the TP to the values as stated in the link. I found that the original TP value was 0.4V and the AMM was 1.95v.

First signs are encouraging as the car does seem to be running better. I'll do a couple of hundred miles and then check the MPG.

Thanks for all your help.

Dave

[chimtvr]

Can i recommend not checking the fuel consumption it will just make you sad.Try doing donuts!!! always makes me feel better