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Rough idle, dirty MAF **Solved** 

 

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 Post subject: Rough idle, dirty MAF **Solved**
Posted: Mon Sep 24, 2007 7:30 pm 
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ok to give everyone a bit of a background it might help. I have dropped a 95 xr8 into a 67 mustang. I had to obtain the wiring diagrams from ford and actually managed to get the thing running. However at some point during the wrapping up of the wires and stuffing them behind the dash something has gone friggin bad.

The first sign of a problem was obvious, a huge plume of smoke coming from under the dash. I eventually traced it to be a buggered reverse lamp and the smoke was coming from the fuse wire on the muzzie ignition. oh yeah the car is running two ignition. the new ford supplies power to the muzzie one which is used to start the car. Initially I thought that I might have some probs with the smartlock in this setup and thought that I might have to supply power to the eec relay and muzzie ignition at the same time but the thing ran , actually it purred.

What struck me as odd was the fuel pump, it doesn't just prime for 2-3 seconds but runs constantly! Now the engine cranks but there is no injector pulse. Does smartlock operate like this coz i thought it actually stop the engine from cranking as well.

Another interesting aspect is the power to the smartlock thing on the ignition barrel. When the key is turned to one I can hear the ecu/bem/tcm powering on as they merrily click away but only a short and sweet voltage "spike" is shown on the multimeter to the ignition barrel smartlock thing. I'm getting a nice healthy spark, just no fuel coming out of the injectors (and yes there is plenty of fuel in the rail)

I have checked all of the regular fuses as the have been put into the car.
I have stuck in a replacement BEM and still no luck. (It is a blue BEM as well)

Is there any easy way to find out if the ecu or bem has been fried? unfortunately v8 ecu's are not that easy to come by in good old Palmerston North (oh to be in Oz again in times like these!). I'm just about to scrap the whole friggin efi thing and put a nice and simple carb on.

Does any guru have any starting points? I'm going to rewire again and remove the muzzie ignition to help diagnose but I'm absolutely stumped. Was getting to the point where I was ready to take the old girl for a drive but looks like the tart likes it in the shed!

Last edited by KiwiDazza on Mon Oct 08, 2007 12:09 pm, edited 2 times in total.

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Posted: Tue Sep 25, 2007 8:14 pm 
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Ok I take it by the flood of replies everyone is stumped. Had another crack at it today and teh problem got worse, now the engine wont even crank. I have tested the circuitry and have come up with...

battery power and ignition power are getting to the BEM. When I turn the key to start the BEM is getting start power in and is also getting starter power out. However this power is not getting to the relay in the engine bay. I'm going through the process of unwinding all of the tape and releasing all of the wires, starting to think that I have somehow buggered some wires.
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Posted: Tue Sep 25, 2007 9:20 pm 
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I could only suggest to pull all the wiring harness out & start afresh. its likely you'll find the fault then on closer inspection on the wire insulations & joints. I'll check the fuse that supply voltage to the smart-lock as well, just to be sure they haven't blown. Have checked the engine fuse-able link?

Just hope the fuses blew before it could do any damage to the ECU.

hopefully someone here will pickup on it & run you through it... all the best & keep us posted!

 

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Posted: Wed Sep 26, 2007 4:27 pm 
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Ahh forgot about the fusible stuff. will get to it this weekend.
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Posted: Sat Sep 29, 2007 11:13 am 
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Ok I have checked out every single fuse and they are all ok. I have replaced the fuel and eec relays.

Now here is something interesting, the buzzing noise is back and it is coming from the dizzy. Could it be possible that the TFI is fragged? Now I'm curious, how does the computer in a V8 know that the engine is cranking? I know the I6 have crankcase sensors but I didn't think the v8's had these. If they do where about can I find the bugger?.

When the key is turn the fuel pump goes but continues to go and doesn't shut off after a few seconds like it used to.

I'm getting the thing to relearn the ignition key just in case it is immobilised but thinking it is beyond that.
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Posted: Sat Sep 29, 2007 3:53 pm 
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I replaced the TFI this arvo and still no go. Swapped in a new BEM and did the relearn thing, no go. I can smeel fuel when the engine cranks but there is no fuel on the spark plugs (well I hope this is an indication)

Other interesting things are
1. The fuel pump doesn't just prime for a few seconds, it keeps on going
2. the voltage on the pinouts on the ecu for all 8 injectors is 12v, as if they are already grounded. Can someone tell me if this is normal.

I'm suspecting that the ecu is F**k but unfortunately I am having a lot of trouble tracking one down to test.
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Posted: Sat Sep 29, 2007 6:20 pm 
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I wish I could help you further man but my knowledge has reach its max capacity with injected V8's. matter of fact its only minimal. as I've mention before, you're better of starting from scratch. start from square one by following the wiring schematic. check & double check every wiring harness until you're absolutely sure everything is ok. the only solution I could think of is acquiring the help of a local rodder!
I know they're more then happy to help out if you're a genuine friendly blokies bloke. :wink:
Its pretty hard for some of us to picture the situation without being there to lend a helping hand.

 

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Posted: Sun Sep 30, 2007 7:53 am 
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Yeah I can appreciate that, when I did the wiring I made sure I kept the mustang wiring separate from the newer ford wiring, with the exception of the brake light which needed to be wired in without ignition power.

I have double checked all of the wiring and none of it is damaged in anyway. I fished out the diagnostic wires last night. Hopefully someone can say whether this is all I need to do but I found pin 2 and connected that to a multimeter and then connected pin 66 to pin 91. The only reading I get on the multimeter is a flat 5.06V. When I disconnected pin 66 the voltage on pins 66 and 2 was 5.06V. From what I understand this is meant to be battery voltage so something is obviously F**k here. At least I feel that I'm closing in on the prob. Courtesy Ford, the local dealer here in Palmerston North has provided a wealth of info and is going to look at the ECU on Monday. It sucks going up there because this is in the showroom!!!

http://www.a***.co.nz/index.cfm?ar ... JI49270156

Every other sensor is within their tolerance. Power levels are all a good healthy 12V and the grounds are all 0.01V so I can pretty much assume that there isn't a short somewhere.

I'll try and load some photos.
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Posted: Sun Sep 30, 2007 8:09 am 
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Sorry the link didn't work. This is the one at the Ford dealer.

http://www.a***.co.nz/index.cfm?ar ... JI49270156

Have uploaded some piccies in the gallery

http://www.fordmods.com/forums/gallery. ... a&meetid=0
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Posted: Sun Sep 30, 2007 8:11 am 
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I see why the first link is buggered, is meant to be www.car.select.co.nz without the dot between car and select...
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Posted: Wed Oct 03, 2007 8:22 pm 
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ok after tracing through some major tangle of wires I finally traced back to the cause of the problem, a bung wire into the ECU.

Once connected back up she now has injector pulse but here comes problem number two.

It takes ages for it to actually start, by that I mean a fair bit of cranking before it will go.

Now she wont idle without pumping the throttle and if the throttle is pressed nothing happens besides it stalling. If you let off the pedal a burst of revs comes before settling down to a really s**t idle.

ECU codes come back with the normal EGR and aircon stuff coz they aren't connected but it used ot run great without these things before the mishap.

any ideas? thought maybe i might have fragged the coil or something.
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Posted: Wed Oct 03, 2007 11:35 pm 
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MAS or MAP sensor?
Its a dumb question but theres always something we might over look. vac leak somewhere maybe.
Did you replace that stuffed wire you've found? might also have to clean the metal contacts completely{connections}.

 

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Posted: Thu Oct 04, 2007 10:05 am 
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yeah replaced the wire completely. Finally managed to get the thing to idle to the point were I could get some codes.

538: which is pretty obvious because I didn't goose the throttle
332: EGR isn't connected

now the interesting ones
116: ECT - suspect that this is a major because I don't have a IAT sensor.
172: Running lean (Will double check the manifold for leaks)
176: Running lean

will try and let the thing warm up a bit more and see if the results stay.

Did find a small leak where the back of the extractors meets the main exhaust but it is after the hego sensors so can't see how this could cause a lean condition, possibly because of the ECT??

Will also recheck the MAF and give it a clean.
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 Post subject: Dirty MAF
Posted: Thu Oct 04, 2007 5:36 pm 
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Have taken the MAF off and found that the intake side was covered with a layer of crap. The shiny bit on the left 'probe' is were I sprayed some electrical cleaner. Will wait until tomorrow to install and see if it makes any difference to the running.

 

 

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Posted: Thu Oct 04, 2007 5:49 pm 
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my EF XR8 Series 2 had major flat spots, hard start was also a problem, and just ran like s**t after i bought it 2nd hand. i took it back to the selling dealer (toyota) being under warranty still and they ended up bringing straight back to me (I was working at the local Ford Dealer at the time) to do the work. Anyway, long story short, there were no codes but ended up being the Air Flow meter even though it was tested by a sparky and said it was good. I know this because i stole the AF meter from a bunky out the back and yeah, was all good. Hard start was also a problem.
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