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 Post subject: Lean Mixture
Posted: Sat Apr 16, 2005 4:51 pm 
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i am having a problem with lean mixture when the engine is under load.
On the dyno at full throttle i am getting an a/f reading of 15. At idle it reads 14.7. Does anyone know if the o2 sensors stay closed loop at idle on the v8's? The tps doesnt seem to knock the o2 circuit open loop at full throttle. Anyone else come across this problem before?
I am only getting 102 rwkw and i'm sure this problem is affecting that.

 

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Posted: Sat Apr 16, 2005 5:35 pm 
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A few things could affect it.

A blocked fuel filer will give you lean mixtures under high load but be ok under light loads. Same with dirty injectors.

You should be able to check if the TPS is faulty. You need a multimeter and check the resistance as you open the throttle, I don't know which wires on teh Ford though.

Try doing all the cheap stuff first before you go spending big dollars trying to fix it. Last thing you want to do is spend $500 finding out it was a blocked $10 fuel filter you can replace yoursefl.
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Posted: Sat Apr 16, 2005 5:40 pm 
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Start with cleaning the MAF sensor, take the electronics off and clean the sensor wires with carby cleaner. The oil form the K&N often coat the MAF wires leading to lean WOT. It probably isn't the TPS sensor as that is only the secondard sensor for triggering open/closed loop opperation, the MAF (load reading) is the primary sensor for that. Its going to be either the MAF sensor or like unclewoja said it could be fuel filter, dirty injectors etc.
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Posted: Sat Apr 16, 2005 6:06 pm 
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If you've got 15 at WOT then thats dangerously lean and may cause detonation.
I had the same symptons when I bought my car - it was leaning out the more throttle it was given and the AF ratio was climbing above 15:1 at WOT. It turned out to be my MAF. I replaced it with a reconditioned one and problem was solved.
Certainly as suggested you could try cleaning the MAF wires first as there's a good chance that it may solve the problem and certainly harmless if the MAF is stuffed anyway.

 

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Posted: Sat Apr 16, 2005 10:30 pm 
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i have cleaned the injectors and fitted a new fuel filter etc. I will try the MAF, cheers.

 

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 Post subject: Re: Lean Mixture
Posted: Mon Apr 25, 2005 12:48 am 
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Neal-50 wrote:
i am having a problem with lean mixture when the engine is under load.
On the dyno at full throttle i am getting an a/f reading of 15. At idle it reads 14.7. Does anyone know if the o2 sensors stay closed loop at idle on the v8's? The tps doesnt seem to knock the o2 circuit open loop at full throttle. Anyone else come across this problem before?
I am only getting 102 rwkw and i'm sure this problem is affecting that.

This sound terribly like my XR8, does it have more power when you back off the throttle a bit?
I ran a pressure guage while out flogging it for a while but no pressure drop was evident? keep us posted if you find the problem as I have been lokking for a couple of months and still no luck!

 

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 Post subject: Thermostat part #?
Posted: Mon Apr 25, 2005 2:40 am 
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does anyone have a part# for this thermostat?
the guy that work at the local parts joint only know about seatcovers & dashmats, so I'd be likely to get a Diahatsu charade part or something else thats made from plastic

 

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Posted: Mon Apr 25, 2005 1:29 pm 
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ok, i have cleaned my maf, yes it was covered in oily crap from the k&n. it feels a little better on the road but have not ran on my dyno and a/f tester as yet due to lack of time. i will run it up early in the week and keep you posted.

kenny, will check the thermo part number for you tomorrow

 

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Posted: Mon Apr 25, 2005 9:09 pm 
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Neal-50 wrote:
ok, i have cleaned my maf, yes it was covered in oily crap from the k&n. it feels a little better on the road but have not ran on my dyno and a/f tester as yet due to lack of time. i will run it up early in the week and keep you posted.

kenny, will check the thermo part number for you tomorrow

I found & bought a 180deg thermostat but still not right, changed fuel filter (again), then had a dozen bourbons and started thinking about chopin & changin' maf sensors and housings, so finally I took the plunge
IT f**k WORKED! I used a sensor calibrated to suit 30# with a 75mm housing in a cleaned up factory 55mm unit, now the thing flies, I mean it lights em up all the way thru 2nd gear without brakes in the dry on decent rubber (well it was B4 I test drove it!)
so I'm taking offers on a 75mm pro-M housing PM me if you R interested.

 

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Posted: Mon Apr 25, 2005 11:06 pm 
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Am I understanding correctly, you are using the Pro-M 30lb electronics on the 55mm MAF body. If so I would be going to a dyno place to check your AF ratios, you should be running so rich it wouldn't be funny, this would give plenty of low down power and probably more up high too but its still not good. You will be wearing out the bores quickly, clogging plugs and 02 sensors not to mention poor economy.
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Posted: Mon Apr 25, 2005 11:23 pm 
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EDXR8 wrote:
Am I understanding correctly, you are using the Pro-M 30lb electronics on the 55mm MAF body. If so I would be going to a dyno place to check your AF ratios, you should be running so rich it wouldn't be funny, this would give plenty of low down power and probably more up high too but its still not good. You will be wearing out the bores quickly, clogging plugs and 02 sensors not to mention poor economy.

yep thats correct! but it doesn't appear to be running rich at all, I tested this by testing how much advance I could use, and found it to detonate at 33deg ,the exhaust emmisions don't have that strong smell or any black smoke ,even under full throttle??
I'm sure there is a computer related problem now ,or I have had 2 dud maf sensors? as for economy ,well I flogged it for about1 hour with less than $10 of juice, usually I don't see the power or economy last that good
I dunno I'm sure i'll find out over the next week

 

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Posted: Mon Apr 25, 2005 11:37 pm 
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Well as long as it works. Can't figure it out because just by looking at the MAF curves for the stock 55mm body and the Pro-M 75mm body you can see they are massively different so I can't understand why its workign for you hehe. I would be checking the AF ratios ASAP just in case.
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Posted: Mon Apr 25, 2005 11:44 pm 
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EDXR8 wrote:
Well as long as it works. Can't figure it out because just by looking at the MAF curves for the stock 55mm body and the Pro-M 75mm body you can see they are massively different so I can't understand why its workign for you hehe. I would be checking the AF ratios ASAP just in case.

yeah Im sure theres something wrong with the electrics somewhere cos it should be lopeing at idle blowing black smoke and have that s**t boggy feel with the calculations i made?
f**k it i'm sick of this car its costing too much I'm considdering buying a BA XR8.

 

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Posted: Mon Apr 25, 2005 11:57 pm 
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kenny wrote:
f**k it i'm sick of this car its costing too much I'm considdering buying a BA XR8.


HAHAHA tell me about it, mines been pretty much off the road for a few years now.
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Posted: Fri Apr 29, 2005 10:32 pm 
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EDXR8 wrote:
kenny wrote:
f**k it i'm sick of this car its costing too much I'm considdering buying a BA XR8.


HAHAHA tell me about it, mines been pretty much off the road for a few years now.

How much work is involved in getting a BA 5.4boss going!

 

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