virtual non runner rover gauge errors 12, 17, 18.........

[MGB3405]

Further to the post below;

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

I now have a virtually non runner the rover gauge error codes are:

12 Airflow Meter
17 throttle pot
18 Throttle pot hi / Maf low

before I throw £400 at parts at it is there any advice?

[yknot]

Before changing all the sensors I would recommend getting a new TPS from Rimmer Bros and then re-setting the ECU and see if that clears your poor running issues.

Worked for me although mine wasn't a non-runner!!

HTH

[s p a c e m a n]

I take it that the starter motor is spinning as fast as normal so you don't have battery/fuse/alternator issues as my first port of call would be the 100 amp fuses that you can't find.

One is next to the starter motor..



And one is near the battery..



Not teaching you to suck eggs but the first basics that I would go for If you're getting MAF error codes would be to try starting the car without it plugged in, as they will normally run without it but won't run if it's throwing out stupid values.

I would also check that I had spark by pulling one of the leads off and sticking a sparkplug in the end.

[blitzracing]

Dont forget the errors are not time stamped- so if you have not had an ECU reset the errors could have occurred at any time in the past. Also as said the car should still run without the AFM plugged in- just badly. Those error codes simply mean that at some point the airflow signal and throttle pot signal have not matched- ie you cant have a high airflow signal with the throttle shut. You can do a throttle pot check with just ignition on.

[MGB3405]

Thanks Guys great advice very helpful as always

Now running (very badly) by fettling the Throttle Pot.

I have re-set the ECU and have the same errors occur.

Unplugged the AFM and it runs more or less the same. (drivable but sputtery (like rev limiter) except at high RPM))

Is there any way to test the AFM I have tried the voltmeter test as discribed on the ACT site

"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. Most defective airflow meters will overshoot to 0.5 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)."

and I got no voltage at all so my assumption is it's buggered or am I missing something ?

not sure if I should bite the bullet and buy both or just AFM

[yknot]

I assume you have tested that you have voltage TO the AFM (5v I believe)? If you have then your AFM is faulty.

Is there someone in your area (Greater London is a big area, can you be more specific) who would let you try their AFM to prove the fault?

I'm miles away otherwise I would let you try mine!

[blitzracing]

Ive never seen an AFM output go dead as such- its normally the loom where its tight as it goes through 90' into the connector. Certainly worth checking both the voltage supplies and earth as suggested. It would be worth doing a resistance check on the output connector to ground with the AFM disconnected to make sure you dont have a short to ground.

Edited by blitzracing on Sunday 20th July 20:04

[MGB3405]

Thanks Blitz

getting a bit out of my depth here, whats the best way to do the resistance check? and where does it ground?

I'm in Surrey, Staines area if any one can recommend somewhere reasonable to take a look for me?

[yknot]

You are about 30 minutes from Racing Green TVR.

Don't want to sound critical of your expertise but it may be worthwhile having a chat with them to save chasing faults if you're not sure of your ability to check sensors, wiring looms, etc.

HTH

[taylormj4]

Hi MGB,
I had similar errors recently, picked up with RG after getting very poor running. I didn't try running past 4000 to be frank as the engine was running so poorly but it did come on with a hot engine like yours.

It turned out to be the MAF, which when replaced, cured the problem.
See: http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Two things you could try:

With RG connected but engine off, try pressing the throttle very very gradually throughout its full range and then back again and see if you can produce every 1% of scale on the RG screen. If you can, throttle pot is probably OK.

With engine running, look at AFM reading on RG in "direct" mode at various revs. With mine, the MAF error was normal when engine running nicely but then when warmed, the misfire would kick in accompanied with the MAF scale bar on RG jumping all over the place from mid 30% up to 100% and back again.

Edited by taylormj4 on Monday 21st July 13:08

Edited by taylormj4 on Monday 21st July 13:12

[blitzracing]

MGB3405 said:

Thanks Blitz

getting a bit out of my depth here, whats the best way to do the resistance check? and where does it ground?

I'm in Surrey, Staines area if any one can recommend somewhere reasonable to take a look for me?

The output of the AFM feeds directly into the ECU, and the ECU will have a resistance value to ground- it will be thousands of ohms- so if you simply unplug the AFM and then use the test meter with the ignition off to measure the resistance between the Red/black (Ground- black probe) and Blue/Green (Air flow signal-red probe) and see what reading you get- if its less than 10 ohms you have a short circuit- if its thousands of ohms its fine.

With the ignition on also check:

Red/black (Ground) to Brown Orange for +12v

To check the ground wire with the ignition on, put you test meter between the red / black wire and the engine block- there should not be more than about .5 volt.

These are just basic voltage checks in addition to the output voltage check you have already done.

Edited by blitzracing on Monday 21st July 18:11

[MGB3405]

Thanks Guys you have been a real help went and bought anew multi meter and:

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.

showing 0.01 volts with very slight change with engine running

resistance between the Red/black (Ground- black probe) and Blue/Green (Air flow signal-red probe)

18.1 on the 20k scale

Red/black (Ground) to Brown Orange

12.1v

the red / black wire and the engine block

0.05v

Rover gauge shows a range of 12% - 94% on the throttle and no output on the MAF at any revs

So my guess is go and get a new MAF and keep my fingers crossed..........

[TV8]

Where in London are you? I am in Bromley and have a spare you can try if you want to see if it makes any difference?

[s p a c e m a n]

They're not cheap, I would try and borrow one for a quick test drive before stumping up the cash. I'm the wrong side of London for you

I made friends with a local landrover owner by pretending that I like offroading just in case I ever need to try and borrow bits

[blitzracing]

On those AFM results- its knackered. The throttle pot needs a tweak as well, but Id leave that alone until you have the car running again.

[taylormj4]

One less expensive thing it could be is the connector into the AFM. If your is anything like mine, the wiring is bent through a sharp 90degree angle into the back of the AFM connector and the bonnet sits on it when closed.

You could try replacing AFM connector. It cost me about a tenner fom memory. Parts available from AES as I have previously posted. Here's a link to where I bought all my bits from:

http://www.autoelectricsupplies.co.uk/product/680/...

I can give you a list of what you need if you like. I found there was enough slack in the cable to cut the old one off completely and start again: new pins, new connector, new waterproofing grommets etc.

Edited by taylormj4 on Wednesday 23 July 12:37

[MGB3405]

Thanks everyone (your helpfulness never cases to amaze me)

Got a new AFM (not that easy) fitted in about five minutes all running fine now, need to get it hot over the weekend to see if original fault is still there fingers crossed...

Mark