i have a AU2 XR8 (220kW) with fuel/air mixture probs.

i had a dyno test done (albiet in darwin) and it only returned 131 kW. but it also showed that it is running too rich. the car has a sports exhaust, H&M headers, K&N filter...normal stuff. it should return around 170 - 180 kW.

the thing is, it feels strong and goes well. maybe something wrong with the dyno.

what causes too rich mixture? i am running PULP. it does run a little rough, but thought that's just the tickford cam. the richness seems to bottom out as the revs increase, actually going of the dyno chart at around 3500rpm. i am also thinking of getting a chiptorque chip, which is what started the dyno testing, but i want to fix the base problem first.

any help would be great.

cheers
mark

What was the ratio?

don't know, haven't got the dyno sheet with me. will get back to you. but going by memory, and i really don't know anything, it was off the chart from about 3500rpm. i don't think it was a good dyno readout as it actually didn't show rpm's, but kph instead!

with that air/fuel ratio. on the dyno print-out its got AFR:P down the left hand side ranging from 12.0 to 28.0 opposing RPM.

the results state it starts at 14.0 (idle) and drops down to 4.0 at full throttle. ??? does this help?

No way it could run at 4, if the printout shows that there is something wrong with the dyno operator. Normally you will see 14:1 at cruise, light throttle and then it will richen up to around 12-12.5 at WOT. The V8's will normally only lean out if there is a problem, if it is in fact going rich I woul be looking at your 02 sensors. Also I would pull a spark plug out and see what colour the deposits are, if it is running too rich the plug will be all fouled up with black deposits.

yes i think your'e right. there may be something wrong with the dyno op. like i said before the low Kw reading is also a surprise as the car feels strong. the thing is this is darwin, and it's the only dyno in town. i might take it to Ford to get them to check it.

is it still possible for it to be that low and still be driveable though? and would it be affecting WOT Kw?

Dont worry about peak power, if it feels strong and doesn't miss up igh then you probably dont have a problem. Dyno readingd vary so much depending on what dyno it is and the operator.

went to ford in darwin (frost ford). the diagnostics showed that ithe car had a problem with the MAF sensor, the IAT sensor, and CPS (camshaft) sensor, along with a Ign circuit malfunction (plugs, leads, coil).

does this sound right to you guys. it seems to run fine, albiet that rich fuel reading. and maybe it does use a bit too much fuel.

can you clean MAF? cause thay cost $685 ea.

Yes the MAF can be cleaned, the best way is to remove the electronics from the MAF body and use carby cleaner to spray the two sensor wires. If you cannot remove the electronics (you need torx security bits to do it) you can just spray the carby cleaner down the holes in the MAF body but that may not be as effective.

IAT sensor fault can also cause issues with AF ratios as it is used in load calculations. They should only cost $30 of so from ford, also check the wiring that leads to the sensor as I have heard a few people with broken or frayed wiring.

I wouldn't worry too much about the other codes at this point, get the AF ratio sorted out first and then see what codes come up. Make sure when replacing any sensor or fixing anything to reset the EEC by leaving hte battery terminals off for a few hours.

thanks heaps EDXR8, will do.

what a great forum this is. i'm ashamed i can't offer more advice myself. i guess i am learning as i go

the IAT sensor costs $17.11

cheers

Now that that is sorted out. Can I ask a question here?

My plugs always come out with this crystilized carbon deposit all over them, and a guy told me he thought my I6 was running rich, should I look at the O2 aswell?

The car can start and idle alright for a few minutes, but then I throw it in drive and move away, when I brake then accelerate back up she coughs and splutters like she's being flooded. This only happens at the very 1st startup of the day?

Hi, reading about your issue with your XR8. I have a similar problem with my 96 NF V8 fairlane on LPG.

See when i brought the car i took it to a mates dyno shop to tune the gas mixture up. While i was there we put it on fuel to see how it run. we found that at about 3000 - 3500RPM the air/fuel mix went off the scale. Similar problem to you. The enigine runs perfect on LPG

My mate who owner of the dyno said you have some issue with the MAP sensor, I have not hooked a diagnostics unit to the car as yet to see what is happening.

I have also spoken with some other mechanics. Others have said if the LPG has ever back fired it will destroy the MAP sensor. See V8 windsors do not have a MAP sensor like the I6 (located on the fire wall). Apparently with the v8's it is built into the MAF sensor.

has anybody dealt with an issue like this?

I live in a remote area and it is had to find people who understand efi systems. I will have a look at the diagnostic codes, see what they say.

Any ideas????

Last edited by hellohumpage on Wed Apr 09, 2008 4:07 pm, edited 1 time in total.

Where is the IAT sensor located?