MAF - Running issues?
Discussion
Hi all,
With thanks to the site and the great members my previous issue of charging and cause for breaking down has cured.
But, alas, I still have a running problem, the car struggles to rev over 2k, I initially thought this was part of my first problem but it seem not.
Trying to identify the problem I have disconnected the MAF and driven the car around the block and then re connected and done the same, there is not a lot of difference. Is this what you would expect or does it point to a faulty MAF.
I had a faulty MAF on an Audi TT and It ran better without the faulty MAF connected.
Any advice gratefully received.
Cheers
Frank
With thanks to the site and the great members my previous issue of charging and cause for breaking down has cured.
But, alas, I still have a running problem, the car struggles to rev over 2k, I initially thought this was part of my first problem but it seem not.
Trying to identify the problem I have disconnected the MAF and driven the car around the block and then re connected and done the same, there is not a lot of difference. Is this what you would expect or does it point to a faulty MAF.
I had a faulty MAF on an Audi TT and It ran better without the faulty MAF connected.
Any advice gratefully received.
Cheers
Frank
I've had a few problems with the MAF and the symptoms I had were misfire above 3500 revs on one, misfire above 2000 on another and cutting out at idle and misfire on another.
I kept going with aftermarket but once I got another OE (two in fact) both have been fine.
Although not perfect I noticed a big difference when I disconnected on one but it was totally fubar.
I didn't look where you were but I have an OE spare you can try if your close enough.
Just read your in Cornwall so don't think that's a good option
I kept going with aftermarket but once I got another OE (two in fact) both have been fine.
Although not perfect I noticed a big difference when I disconnected on one but it was totally fubar.
I didn't look where you were but I have an OE spare you can try if your close enough.
Just read your in Cornwall so don't think that's a good option
If you have access to either an ECUMATE or better still the software blitz produces the cable for Rover Gauge.
Check your throttle pot sensor voltage is correct.
A bit of a guest but a good idea to check TPS as that's what the Ecu reads for fuel and air requirement amongst other things.
Check your throttle pot sensor voltage is correct.
A bit of a guest but a good idea to check TPS as that's what the Ecu reads for fuel and air requirement amongst other things.
There is a bit on testing the AFM and throttle pot about 1/3 of the way down the page. (With thanks to Mark Adams). This test will only tell you the AFM voltage output is somewhere near correct, it wont tell you if the ECU is seeing the voltage, but RoverGauge will when it arrives.
http://www.g33.co.uk/pages/technical_fuel_injectio...
http://www.g33.co.uk/pages/technical_fuel_injectio...
Edited by blitzracing on Saturday 19th August 22:04
Hi,
What a great bit of kit the rovergauge is!
The car seems to be running ok again, I think taking the MAF sensor connector on and off has made a better connection. The faults codes showing where 12, 18 & 19, AFM and 2 throttle pot, Hi and Low. The Air flow is 34-35% so seems like the fault has gone.
I have cleared the codes and been out for a spin, so far so good, will go for a longer run at the weekend and see if any of the fault codes re-appear.
Thanks for your help.
Frank
What a great bit of kit the rovergauge is!
The car seems to be running ok again, I think taking the MAF sensor connector on and off has made a better connection. The faults codes showing where 12, 18 & 19, AFM and 2 throttle pot, Hi and Low. The Air flow is 34-35% so seems like the fault has gone.
I have cleared the codes and been out for a spin, so far so good, will go for a longer run at the weekend and see if any of the fault codes re-appear.
Thanks for your help.
Frank
Here we go again!
Took the car out Saturday morning, all seemed good, 5 Miles up the road the misfire issue starts again. I managed to limp it home and parked up.
I went to read the fault codes on the Rovergauge I had a starting issue, the engine carried on cranking, even with the key removed, I managed to disconnect the battery to stop this. I then re connected the battery and tried to start the car again, nothing! pump priming and ignition lights but wont crank. Looking under the bonnet it seems that I have burnt out the "hot start kit" wiring, I am guessing this was due to a sticking relay causing the starter to continue to crank, and the no cranking issue due to the original hot starting issue as the car started ok this morning. Does that sound right?
Anyhow, of course disconnecting the battery cleared any fault codes so no idea what codes would have been there after getting home. This morning I have move the car and it idles ok but will not rev over 2K again. I ran it up to temperature and used the Rovergauge again.
Its was showing fault - Resister tune out of range
This is the first time I have seen this code, and after clearing has not come back while car is idling.
All Rovergauge readings seem ok apart from the lambda fuel trim which shows on longterm, odd, -26% even, -91%. should these be so far apart? and would this be due to or the cause of the error code?
As always I would really appreciate any advice.
Many thanks
Kind regards
Frank
Took the car out Saturday morning, all seemed good, 5 Miles up the road the misfire issue starts again. I managed to limp it home and parked up.
I went to read the fault codes on the Rovergauge I had a starting issue, the engine carried on cranking, even with the key removed, I managed to disconnect the battery to stop this. I then re connected the battery and tried to start the car again, nothing! pump priming and ignition lights but wont crank. Looking under the bonnet it seems that I have burnt out the "hot start kit" wiring, I am guessing this was due to a sticking relay causing the starter to continue to crank, and the no cranking issue due to the original hot starting issue as the car started ok this morning. Does that sound right?
Anyhow, of course disconnecting the battery cleared any fault codes so no idea what codes would have been there after getting home. This morning I have move the car and it idles ok but will not rev over 2K again. I ran it up to temperature and used the Rovergauge again.
Its was showing fault - Resister tune out of range
This is the first time I have seen this code, and after clearing has not come back while car is idling.
All Rovergauge readings seem ok apart from the lambda fuel trim which shows on longterm, odd, -26% even, -91%. should these be so far apart? and would this be due to or the cause of the error code?
As always I would really appreciate any advice.
Many thanks
Kind regards
Frank
A few things to look for here- that screenshot of RoverGauge looks just fine, so at least the AFM is connected and working. The tune resistor out of range seems quite a common one, even when the tune resistor is just fine. There has been discussions in the past that error is enough to throw the ECU into fall back mode, but Ive never personally seen it, the car runs just fine with the error logged. Anyway you are running map 5 in the screen shot, so that's not in fall back anyway. It will have cleared all the error codes down if the battery has been disconnected , so you may have lost anything else more meaningful. As for the trim, dont get too hung up on it, they are never even right to left due to the way the plenum feeds the air in from one side, its certainly not the reason for you 2k limit. The ECU will need to re learn the trim if its been reset with a power off- you should see it in action on a hot engine at idle, where it will start at 0% and slowly move until it settles- typically around 2.5 minutes. Back to the fault- you did get some clues earlier with the mismatch between TPS and AFM- the ECU is smart enough to work out if the throttle is open, then there should be airflow, and likewise if the throttle is shut, there should be very little. You may have a faulty TPS- they go open circuit and it cuts the fuel off when they do at a certain point in the track movement, and this will get logged as a TPS/ AFM error. You can do a basic TPS test in RoverGauge by simply turning on the ignition and depressing the throttle, and making sure RoverGauge reads from a few percent to 85% or more at WOT, with no drop outs. Its not always apparent when the engine bay is cold, as heat can affect the TPS.
Hi.
A shot in the dark, started the car, still misfireing at 2k. Took it for a run and then checked the fault codes, none!
Whilst removing the fried hot start wiring I noticed some insulation tape flapping about. This was holding an inline lucas rd953066 resistor, I removed it, car won't start, replace it and it starts.
Having removed it and put it back a couple of times, it's either my imagination or the problem is now at 3k.
Am I grasping at straws or could this little fella be the problem.
If so, where can I get one, Googled it and can't find a stockist.
I WILL get to the bottom of this!
Cheers
Frank
Should have added, tested the tps on a hot engine bay and all good, 7% - 96% with no glitches.
A shot in the dark, started the car, still misfireing at 2k. Took it for a run and then checked the fault codes, none!
Whilst removing the fried hot start wiring I noticed some insulation tape flapping about. This was holding an inline lucas rd953066 resistor, I removed it, car won't start, replace it and it starts.
Having removed it and put it back a couple of times, it's either my imagination or the problem is now at 3k.
Am I grasping at straws or could this little fella be the problem.
If so, where can I get one, Googled it and can't find a stockist.
I WILL get to the bottom of this!
Cheers
Frank
Should have added, tested the tps on a hot engine bay and all good, 7% - 96% with no glitches.
Edited by Franky boy on Tuesday 29th August 17:24
Maybe some help in this old thread:
https://www.pistonheads.com/gassing/topic.asp?t=11...
And from another forum:
"When visually inspecting the EFI Cable Harness Assembly, one unusual component that's particularly conspicuous is the resistor that Rover included on the Engine Speed sense circuit. This resistor should NOT be confused with the Tune Resistor. This circuit is the only connection between the ignition system and the fuel injection system. A damaged or loosely connected resistor would likely result in an open circuit, leaving the ECU wondering about engine speed.
In our example system this resistor is marked "Lucas", "RD953066", "83630A", and "892Q". The resistor should provide about 6.8k Ohm resistance.
Its there to limit the back emf from the coil damaging the ECU when the coil fires, as its the RPM signal to the ECU, and if it goes open circuit the ECU will cut the fuel after a second or two as it thinks the engine has stopped."
https://www.pistonheads.com/gassing/topic.asp?t=11...
And from another forum:
"When visually inspecting the EFI Cable Harness Assembly, one unusual component that's particularly conspicuous is the resistor that Rover included on the Engine Speed sense circuit. This resistor should NOT be confused with the Tune Resistor. This circuit is the only connection between the ignition system and the fuel injection system. A damaged or loosely connected resistor would likely result in an open circuit, leaving the ECU wondering about engine speed.
In our example system this resistor is marked "Lucas", "RD953066", "83630A", and "892Q". The resistor should provide about 6.8k Ohm resistance.
Its there to limit the back emf from the coil damaging the ECU when the coil fires, as its the RPM signal to the ECU, and if it goes open circuit the ECU will cut the fuel after a second or two as it thinks the engine has stopped."
Edited by N7GTX on Tuesday 29th August 17:45
Its just a dropper resistor that limits the voltage the ECU sees from the coil primary- looks fancy, but its just a resistor. If this is at fault you will get an inconsistent RPM reading in RoverGauge, as this trigger pulse controls the ECU injector timing and fuel pump operation so its pretty critical. What is the car rev counter doing at the point of failure- any erratic movement? Another possibility is a failing coil, but RoverGauge wont pick this up easily, although you do tend to see very high fuel trims at the point of misfire, as the lambda probes can tell the difference between a lean mixture and un burnt mixture, so it adds load of fuel to try and make the probes switch.
Just a warning shot about the ECUs processing power- if you rev it to 4k plus you may loose sensor data erratically, as the ECU is not fast enough to update all the outputs to Rovergauge and control the injection at the same time, so if you are just checking RPM, turn all the other sensors off to get the best reading.
Just a warning shot about the ECUs processing power- if you rev it to 4k plus you may loose sensor data erratically, as the ECU is not fast enough to update all the outputs to Rovergauge and control the injection at the same time, so if you are just checking RPM, turn all the other sensors off to get the best reading.
Id simply user something substantial like a 1 watt one, juts because the wires are thicker and body heavier so its more robust- but having said that there is no reason to replace it unless its highly corroded, I doubt for one minute this is your point of failure, as why would it be RPM sensitive?
Hi,
Loosing the will!
I have now changed plugs, leads, coil, rotor arm. Removed plug extenders, all good on rovergauge and still badly missing at 2k.
The plugs I removed where really sooty, so running rich, all of them the same.
I have tried removing the lead from each plug to see if I actually have a mis fire at idle but can't really tell, and it gets so hot it becomes painfull! Is there another way of checking?
I'm just wondering what the next step is, ignition module?, do the ecu's have a history of failing?
Would a faulty lambda cause over fueling and a missfire? In my mind no but open to other opinions.
As always, help, advice, thoughts and opinion gratefully recieved.
Frank
Loosing the will!
I have now changed plugs, leads, coil, rotor arm. Removed plug extenders, all good on rovergauge and still badly missing at 2k.
The plugs I removed where really sooty, so running rich, all of them the same.
I have tried removing the lead from each plug to see if I actually have a mis fire at idle but can't really tell, and it gets so hot it becomes painfull! Is there another way of checking?
I'm just wondering what the next step is, ignition module?, do the ecu's have a history of failing?
Would a faulty lambda cause over fueling and a missfire? In my mind no but open to other opinions.
As always, help, advice, thoughts and opinion gratefully recieved.
Frank
The lambda probes cant tell the difference between a lean mixture or an un burnt mixture as both have a high oxygen content that the probe monitors- so the ecu could just be trying to compensate for a misfire by throwing in extra fuel. There are some clues here, where you tend to see very high levels of short term trim on the side of the V8 thats is misfiring, but thats the best RoverGauge will show if its and ignition issue. As for manifold temp- a less technical but perfectly effective method is to try and melt a cable tie on the exhaust header, a non firing cylinder wont melt at all or as easily. Mind you dropping a plug wont cause the engine to limit to 2 k- this is very much more fundamental. Its worth checking the rotor arm aligns with number one cylinder on compression at around 10' BTDC- it could be possible if the dizzy has been removed that the rotor arm is far enough away from the HT lead pick up point to prevent reliable spark transfer. If you have access to an old style Crypton tune that will display HT voltages on a scope, you will see open circuits in the HT as very high voltages as the coil voltage generated are much higher before it sparks. Also worth checking the timing is advancing as it should with a strobe as the bob weights can rust up so you get no timing advance- but this leads to a flat engine, not a misfire. As a basic test if you can unplug the king king from the coil to the distributor (dizzy end) and tape the unplugged end at least 15mm from the chassis, you should get a spark that jumps that distance easily when you crank the engine- that will show the HT is good to the dizzy, so the next point is check the dizzy cap has its carbon brush still and the rotor arm is in the right place to allow that voltage to reach the plugs. If you have a strobe- try triggering of each plug lead and see if they are the same?
Edited by blitzracing on Saturday 2nd September 20:10
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