Air Fuel Ratio Problem

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bracpan

Active Member
I had the car on a rolling road and all was perfect, but just after the car started running rich ( I have a Stacks Labda gauge fitted) it was also lumpy etc on tick over but on boost ran ok.
Competed with it last weekend and half way up on the first run it poped and banged then cleared and run good all weekend starting and runing perfect, pulled my best finish speed ever. ( cant read the gauge when competing)
Took the car out tonight and its running smooth but notice that its fual air ratio is not going below 14 on boost, ( it was mid 11's on the rolling road) took the plugs out to check and they are a chocolate brown colour and the car didnt seem to knock but its not easy to hear that now as its stripped out....
I cant figue out why its gose to one extreme then the other?
Any ideas please? As i am out again next weekend. HELP..
 
J

Jon Olds

Well-Known Member
Just been through something similar. AFR gauge used to read spot on, then all over the place. Lost power. Sounded awful. Turned out to be a boost leak. Lesson learned the hard way. Prior to this I had changed plugs, AF meter, rotor arm, cap, leads, checked fuel pressure etc etc.
Now I have made two adapters to bung up the pipework, one with a schraeder valve in, so I can use a footpump to pump it to 20psi and listen
Hope this helps
Jon
 
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bracpan

Active Member
Thanks guys much appreciated, I have a fuel regulator on the way to try but will have a good check to see if I have any leaks etc, and will clean the MAF again....I have had simular problems before but it usually makes it run rich, this has switched to the dead opposite. Also had some advice from the usuall guys so I have plenty yo work on over the weekend....shame no one closer with parts I could swap and check out.
many thanks
Phil
 
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bracpan

Active Member
Still racking my one brain cell to find the problem, found a small fuel leak just before the filter and also the fuse protecting the pump as getting hot and burnt the holder,,,so great repaired it all and a slight improvement readings now in the 12's but still not right.
if I had it mapped with these problems could the map now be so far out? Im clutching at straws now....
I also cant get the dam phillips head screws out of the regulator so will probably have to drill them out to swap it over...wht didnt they fit hex or allan headed bolts not effing phillips heads....
 
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MarkTurbo

Well-Known Member
Phil, I'm no expert on electrics but the fact that the fuse holder was getting hot doesn't sound good. Might be worth looking at the wiring on the pump (earths etc) or maybe even the pump itself as if the pump wasn't getting the correct voltage or is getting tired that could cause it to not supply enough fuel and give you the lean readings on your wideband.

Fingers crossed it turns out to be something simple for you to sort out.
 
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pulsarboby

Guest
as mark said above phil

with regard to the screws...either get a pair of long nose mole grips on them or get a small chisel and give them a sharp wallop to crack them loose
could still be that fpr at fault here
 
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bracpan

Active Member
Yes I am still hoping its the FPR as the pump seems to be fine it pumped out 1.5 litres of fuel in about 15+ seconds, i think the fuse holder from Halfords was the problem as it was a rubber one, and small blade fuses I have now fitted a bigger stronger one with normal size blade fuses. the wiring is all new and plenty big enough plus I have checked the switch out. ( I am a spark by trade). If I remove the pipe from the FPR I can feel the air being sucked in but it makes little difference to the readings I would have thought it might have increased the pressure on the fuel and gone rich, but no. So it is hopefully the regulator, I am just woundering it it was playing up the mapping could still be out?
I am supporse to be racing on the weekend so all my fingers are crossed...I also cant thank you all enough for your ideas.
regards
Phil
PS Just went out with a chisel and lossened the screws, many thanks for the tip.
 
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B

bracpan

Active Member
Jon Thanks
I done think its a leak on the intercooler pipes as when that happens the car misfires and goes very rich, Im just hoping its not the MAF but I have cleaned that and again the car went rich when it was dirty before.
The car was playing up a few days before before going rich then back to normal now its gone week so really hoping its the regulator.
It used to be much easier problem solving with carbs and points etc...at least there was less to check..lol
 
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bracpan

Active Member
Sometimes I wish I had taken up golf or something less stressful, fitted a new regulator and gues what, No f***ng difference ( but a big thanks to Bob for sending it so quickly) I have now totaly run out of ideas and I am just praying its the sensor thats faulty not the mixtures,,,but with my luck this year I doubt it very much. Will take it to the Rolling Road on Friday on the way to Prescott if we cant solve it ill be back home for an early bath...and another meeting missed.
 
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bracpan

Active Member
Well its not the pump/pumps either as I disconected the 044 and run it on the in tank pump and its still the same....not much left to test.
Hope Indigo-GT can solve this for me on Friday,,,,
 
warpspeed

warpspeed

Well-Known Member
Also check engine to chassis and battery earth and pump to body earth, I had a supra before with problems similar to yours with erratic afr's, I took earth straps off and properly cleaned everything, never had the problem again.
 
K

kirko

Member
you could always get a fuel pressure gauge and see exactly whats going on with the fuel pressure
and whether it is droppping
 
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bracpan

Active Member
The pumps are each wired seperatly so the chances of having both with wiring problems is very low, apart from that im a spark by trade so when i wired the 044 I went over the top, with large wire size and a very clean earth...will double check the voltage again tomorrow to make 100% sure.
I hope to have the pressure checked on Friday, I just have a funny feeling its something else...
Thanks again for the surgestions much appreciated.
 
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pulsarboby

Guest
i take it your running a z32 phil? could possibly be that thats playing up and ecu's not getting correct info from it.
that would be my next port of call after the fpr and wiring which youve already checked
also check the rotor arm grub screw as that may have come loose and rotor arm moved on shaft hense giving slightly incorrect ignition firing
 
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