Rovergauge help please

[A900ss]

For various reasons I haven't driven my car for about 4 weeks and its now running like a dog.

It's popping and banging and feels like its running on 6 or 7 until it clears its throat. (Well, it was but now it can't seem to clear its throat at all!!)

I therefore hooked it up to Rovergauge to see if any fault codes and there were none. It is running at 100% long term and short term trim for both banks. It also stinks of fuel and emits white smoke (petrol?) from the exhausts. It has now got so bad I need to hold my foot on the throttle so it doesn't cut out.

Screen shot at idle:


Screen shot stationary but with some revs:


Screen shot whilst driving:


Since I took these screenshots, its got worse and I'm having to use more throttle just to stop it from stalling.

Like I said, both long term and short term trim are at 100% and I notice that the fuel range that all screenshots I'm working in are deep in the bottom orange zone.

The last time I drove it was 1,000 miles in France and it run like a dream getting 25/27MPG which is the best its ever given.

I have recently replaced all plugs, HT leads, rotor arm, ignition amp, dizzy cap, fuel regulator and vac advance on dizzy. Replaced 6 months ago was the coil.

I know most of the above are electrical and with 100% trim, I'm guessing this is a fuelling issue rather than spark issue.

AFM? It's the original AFM to the best of my knowledge but I don't want to replace items just for the sake of it (especially an AFM as they are quite expensive).

Thoughts most welcome.

Karl

PS -How much does CANEMS/Megasquirt/Emerald cost fully fitted? I'm getting fed up with this.

Edited by A900ss on Thursday 31st July 17:14

[EGB]

My sympathy Karl. I have similar probs now after running well.
No fault codes etc. Have good sparks.
Working on it at the moment. May take it to our TVR expert who has the electronic bits to try one at a time to see which one does the trick. Could be an iffy AFM , throttle pot, stepper, dizzy, fuel pump, injectors, relays, lamdas, coil, ig amp and ECU. Hope it's only one of these. Hope!
Perhaps an Ecumate may show something? Hope Mark can give some advice.

Edited by EGB on Thursday 31st July 22:57

[yknot]

Hi Karl,

You shouldn't have taken it away from Blighty, and no doubt filled it up with SuperU gas!! Haha!

Seriously though have you checked the wiring to the injectors? Another poster here recently with over-fuelling caused by a shorted wire to the injectors, although I would have expected a fault code, but if I remember correctly, nor did he?

HTH

P

[TV8]

Hi Karl,
Try an ECU reset. Have you got a standard alarm?

[PH430]

Hi Karl,

-100% is a lean mixture.
Your maf reading on idle is very high. It shoud be 32 til 35%.
You have non throhlle reading. TPS set shoud be 0,32volt.

I think your running in the limp home mode.

Ecu re-set shoud be the first to do.

[PH430]

Hi Karl,

I mean with -100% it is a misefire.

This is something for Marc Thompson of Blitzracing

[A900ss]

I thought -100% means the ecu is pumping too much fuel in so the trim to -100% is to reduce the fuel going in but as it's At -100% (ie can't help anymore), it's running rich.

It is the standard alarm so I will try an ECU reset. I assume that you just unplug the ECU from the cables in the footwell?

[danbourassa]

It does not appear to be in limp home mode since RG indicates map 5 (limp home is map 0). PH430 is correct about the MAF reading. It's way too high. This is forcing the map selection to one of the bottom two rows (the black highlighted cell). You should probably be on the 2nd or 3rd row. Unfortunately, it does appear to be a fault with the MAF.

[danbourassa]

Try unplugging the MAF to see if the engine runs better. Since you don't have a fault code, the ECU is actually using the MAF data, as bad as it is. Unplugging it should set a MAF fault. The ECU will then fuel based on RPM and TPS. This is usually not as good as using the MAF signal, but, in your case, it should be an improvement.

[A900ss]

Ok, ECU reset just done and fired her up.

She was running beautifully at idle after this. The car didn't get warm enough for long term trim to move from 0% after the reset but the short term trim was rock solid at 0%, engine running great at idle.

Quick dab of the throttle and the car went back to being a dog again. 1500RPM to 700 RPM hunting. Short term trim all at -100% again. All from touching the throttle (which I'll need to do if I want to actually drive the thing repeat her than just idle it!!!)

A few questions about the AFM:

How can I check it's the AFM and not the connections to it?

Are they just straight swap over to a new one or do they need calibrating?

Where is a good source of good AFM's as I know Blitz doesn't rate the copies?

Thanks in advance again.

Karl.

[A900ss]

danbourassa said:

Try unplugging the MAF to see if the engine runs better. Since you don't have a fault code, the ECU is actually using the MAF data, as bad as it is. Unplugging it should set a MAF fault. The ECU will then fuel based on RPM and TPS. This is usually not as good as using the MAF signal, but, in your case, it should be an improvement.

Ok, unplugged the MAF and these are my thoughts:

Let's use my car running normal as a base of 10

Before the ECU reset this evening it was idling about a 3 out of 10 and eventually stalling itself whilst idling.

After ECU reset, back up to 10 again however after a dab of the throttle it went nuts again, so back down to 3 out of 10

AFM unplugged and the idle is now about an 8/10. Dab of throttle and still about an 8/10. Back to idle and still an 8/10. It is not as good as normal but nowhere near as bad as it was. Still feels a bit 'fluffy' in engine pick up and idle though, if that makes sense with the AFM disconnected but then again I'm not sure how it's supposed to feel with the AFM off.

My battery has died on the laptop so can't connect Rovergauge up with MAF unplugged but will RG still give me trim values with the MAF unplugged because I can check them in the morning if it does?

Thanks.

Edited by A900ss on Thursday 31st July 21:02

[danbourassa]

Don't bother with the trim values. They are meaningless until the big problem is fixed.

[MGB3405]

hi good advice on my post here re AFM hope it helps

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[A900ss]

AFM's, what's good and what's not?

£168 from Clevor Trevor but seems to be pattern part
http://www.clever-trevor.net/TVR/Parts_details/E20...

Power want £250 but looks to be genuine Lucas that has been reconditioned
http://www.powersperformance.co.uk/store/slug/air-...

Any other (better) options?

[Chuffmeister]

This is a little strange that you should post this. I've finally managed to get my car running today (MOT tomorrow). I had this problem last year and did a little reading. Jamie on this forum also had the same problem and narrowed it down to the lambda heater circuit. One of the symptoms is that it runs rich -100% on the longterm trim with a faulty heater circuit. It will do this because it runs closed circuit below 3000rpm and at idle. Above 3000 rpm it runs open loop. The short term trim is constantly changing, so is compensating and the lambdas are working.

Today, I changed the silver relay on the umbilical cord (not the fuel pump one). Problem solved. Now looking more lean on the longterm trim.

It may be worth checking that the relays aren't sticking and giving you this problem. HTH.

[TV8]

eBay is a good source of genuine AFM's.i have one somewhere since the 20am version up-grade but can't remember where I put it!

[A900ss]

This one appears to be genuine Land Rover. Has anybody used these people? The Brtipart AFM'S are about £100 so don't want to pay twice that for this one if it turns out to not be genuine just with a LR sticker on it.

http://www.lrdirect.com/ERR5198-supplied-by-BRITPA...

[blitzracing]

I will confirm with Dans post- that AFM output is far too high. The problem is the ECU thinks there is lots of air going in, so it puts in lots of fuel. In most cases the output from a defective airflow meter will be in the range 2.0-2.5 Volts at idle, which is a viable value. This represents a moderate load and will cause heavy over-fuelling without setting a fault code.

Testing is performed in the following manner. Peel back the rubber boot on the airflow meter connector and leave it plugged in to the airflow meter. Set up the digital multimeter to read voltage. Insert the negative probe into the Red/Black wire (sensor ground), and the positive into the Blue/Green wire (Airflow signal).

Turn on the ignition, but do not start the engine. The meter should immediately indicate a reading of approximately 0.3-0.34 Volts after the initial "warm up" spike. Most defective airflow meters will overshoot to 0.8 Volts or higher, and take at least 2 seconds to come down to the correct voltage.

Now start the engine, and the reading should rise to 1.6 Volts (3.5 Litre engine) to 1.75 Volts (5.0 Litre engine).

[EGB]

blitzracing said:

I will confirm with Dans post- that AFM output is far too high. The problem is the ECU thinks there is lots of air going in, so it puts in lots of fuel. In most cases the output from a defective airflow meter will be in the range 2.0-2.5 Volts at idle, which is a viable value. This represents a moderate load and will cause heavy over-fuelling without setting a fault code.

Testing is performed in the following manner. Peel back the rubber boot on the airflow meter connector and leave it plugged in to the airflow meter. Set up the digital multimeter to read voltage. Insert the negative probe into the Red/Black wire (sensor ground), and the positive into the Blue/Green wire (Airflow signal).

Turn on the ignition, but do not start the engine. The meter should immediately indicate a reading of approximately 0.3-0.34 Volts after the initial "warm up" spike. Most defective airflow meters will overshoot to 0.8 Volts or higher, and take at least 2 seconds to come down to the correct voltage.

Now start the engine, and the reading should rise to 1.6 Volts (3.5 Litre engine) to 1.75 Volts (5.0 Litre engine).

Nice and clear and easy. Will test mine also.

[MGB3405]

Clever Trevor no longer stock despite being on site, i used David Gerald not OEM though......