Tachyometric Relay F***ed?

[DirtyFlare 0]

I went out to get some beers and got half way when my car wouldnt rev past 3k rpm, it then died on me . it would start but not idle after this, when i got it started and opened the throttle it would rev up to about 3k rpm and start back firing, although it was fine if u reved it to say 2k rpm when i left it, kicked it a few times it would start. obviously when it had cooled down slightly.

 

So im thinking having read various topics a while ago, cant find any, would it be the Tachyometric relay getting hot? or would it be the igition amp? or even the fuel pump, but why would it and start fine then about 5 minutes down the road, decide it didnt want to rev or idle, the idling deffinitly has nothing to do with the sad as i replaced that and set it up a while ago.

 

Any help would be great as well Ive now got a car that is stuck outside a builders yard (luckily its sunday tomorrow and they wont be in, like they have a choice now )

Edited April 12, 2008 by DirtyFlare

[DamirGTI 327]

Id say maybe AFM (carbon track worn out in one position) or the ignition amp.

 

But make usual ignition components check just to be sure , starting from the plugs and move forward to - leads , dizzy cap , rotor arm , dizzy signal cable , connectors/wiring , ignition amp. , coil .

 

Rgs !

Damir

[richard 0]

When mine backfired, it was the coil breaking down.

 

followed by me being on the back of a tow truck 15 mins later.

[DirtyFlare 0]

Thanx for the replies guys.

 

I just had a look at the HT leads and spark plugs. I found that one of the Sprak plugs had some corrosion on it and the Ht lead was blackened, not good. I checked the ends on the distributor cap and the one that feeds the ignition coil was badly corrorded too, i attempted to clean them up but it wasnt great. I start the car and it was fine, reved at 1.5k then lowered to 1k. I tried revving the car up and it was fine, bounching off the limiter. But i left it idling for a couple of mins came back and tried to rev it and i had the same problems as before; would not rev past 3.5k rpm and constanly back firing, when i lifted off the throttle the car died and would not start.

 

So would this mean that the HT lead(s) are breaking down under the higher temperature or could it be something else that doesnt like heat?

 

Im changing the HT leads, when i can find someone who sells the right ones and obviously the spark plugs as well.

 

The HT leads are identical to the ones in this picture, does anyone know where I can get them? ECP dont sell them neither do my local motor factors

[Rob_the_Sparky 9]

GSF and my local factors do (about 6 months ago) but they had to order them in, no longer kept in stock...

[richard 0]

Get yourself some NGK sparks BP714ES for a 1.9 block and i think its BP713ES for the 1.6 but check that first. Halfords have them, and gap them to 0.8 for standard or 0.9 if you have a good ignition system.

 

Leads, cost me around £18 and had to wait a day for them to arrive. (and i oddly got 6 leads..2 king and 4 spark leads

 

For what is little money really (in terms of car parts) id say replace them and even if it doesnt fix the problem you wont have to worry about the leads for a while. (although i think it will fix this)

 

Ignition amp would cause something similar to happen but i'd expect it to be higher up the rev range and getting progressively lower as the amp heats up. (thats around 25 iirc)

[DirtyFlare 0]

I managed to source the HT leads in the end, local motor factors are great

 

I changed the HT leads, spark plugs and distributor cap & rotor but still had the same problem, fine when cold, when hot would not idle or rev past 3k rpm back firing like a mofo.

 

So I changed the coil to the one that was on there when I got the car, was in good working order but I changed it anyway, and still had the same problem.

 

I've got a new coil and ignition amplifier on order and will be picking them up tomorrow so I hope this will sort it, if not, well erm, back to square one

[boombang 2]

checked the resistance of the ECU coolant temp sender? Can't remember for the life of me what it should read hot and cold though, but definately worth checking.

[DirtyFlare 0]

I changed that about a month ago, so should be ok. when i changed it i definitely noticed a difference in my fuel consumption so I think it is working as it should

[DamirGTI 327]

Can you rev the engine from 1000 up to 6000rmp. when it's cold ? does this problem happened only when the engine warms up or is it same hot or cold ?

 

Rgs !

Damir

[DirtyFlare 0]

i can rev it when its cold to 6000rpm, just not when its hot. So yes it only occurs when the car is hot

Edited April 17, 2008 by DirtyFlare

[DamirGTI 327]

..weird i was thinking that it could be the AFM (when the carbon track gets scratched/damaged in one precise position then the engine wont rev past this position and when the AFM wiper arm reaches this position the engine shuts off or/and start to misfire/backfire/hesitate until the arm passes from this scratched/damaged position back on good undamaged .. if it's only lightly scratched in one position .. but that will be same hot or cold ..)

 

If the problem is "temp. sensitive" as you say then it could be the ignition amp. or coil .. try with some known good working ignition amp.

 

 

Rgs !

Damir

[DirtyFlare 0]

Ok, ive just changed the ignition amp and coil, still same problem although it was a little better as I managed to get around the block before it started.

 

What now? could the fact that the exhaust is blowing as I need new springs (which ive now got) have any thing to do with it?

[DamirGTI 327]

Bugger

 

Dunno if this can help , but do you have a spare AFM to try out ? The Tachy relay does get hot (i almost catch fire because of the melting/burning tachy relay ) but if it's dodgy the car will not start at all or it'll cut out completely during the driving .. and often you can start the car again after a few min. when it's cool down but shortly after all this will repeat (this is when a diode breaks down inside the relay..)

 

Rgs !

Damir

[DirtyFlare 0]

I just changed the AFM over to another one i had lying around and still same problem, fine when cold, but when warm doesnt want to know.

 

i also noticed that the rev counter was jumping about a bit, instead of the needle moving smoothly it would jump a 500 rpm or more. does this point to the Tachyometric Relay? Where exactly is it?

[richard 0]

tachymetric relay can be found under the dash near the steering column. sitting in the drivers seat it will be on the right hand side of the column, which you should be able to see looking into the cubby hole.

 

Easier to remove that bottom panel though to get at it, but can be done without.

 

It should be mounted with the ECU, although this seems to depend on the car (ie who's had it apart before)

 

Im not convinced its the relay though, but seeing as you've already approached pretty much everything else, it wont hurt. Note that a bit of brown discolouration on the tachy is usual.....but if it has a burnt look on one of the pins then its close to (may already have started to) break down. It normally though will just kill the fuel pump supply, rather than do anything else in my experience.

[DirtyFlare 0]

I found the Tachyometric Relay, thanx for your help. On taking the bottom part of the dash off I was horrified to find choc-blocks, exposed cable and masking tape used as insulation tape

 

I think it is due to the fact that my car once had a working alarm, now it just has an immobiliser and who ever had the car before me thought it would be a good idea to remove it. Also the car should have factory remote locking, I don't have a fob for that either

 

But any way back to the relay. There doesn't seem to be any discolouration on the pins of the relay. I'm going to get another one just so that I can remove that from the equation.

 

What else could be causing this problem? Is there any other relays/switches that don't like heat?

[Tom Fenton 1,526]

If I were you I'd spend a couple of hours with a soldering iron and some heat shrink sleeving and get rid of the nasty bodged wiring. It may or may not be causing a problem at the moment, but it will surely let you down at some point.

[DirtyFlare 0]

Ive managed to remove quite a bit of the old alarm wiring and the car still starts Ive repaired the exposed wiring as well.

 

But this turned up this morning

Lets hope it sorts things otherwise I'm back to square one

[philfingers 5]

fuel pump, ecu?

[yeti-dj 7]

Jsut to add my 10p worth but i recently replaced my fuel pump as the old one packed in, and once i had fitted the new pump the car would start fine and idle no bother but it wouldnt rev above 2500-3000rpm and back fired if you tried to rev it any harder.

 

Maybe worth changing the pump for one you know that works just to be sure.

 

hope this helps...

[daveholman 0]

As Philfingers said it could be the ECU, when my alternator went it did a very similar thing when the battery was running flat. The electrician I took it to reckoned that the ECU wasn't working correctly as there wasn't enough power and as such was affecting the firing and timing. I'm not that mechanical so can only speak from experience unfortunately but it's got to be worth a look.

[DirtyFlare 0]

Thanx for all your help. I changed the tachymetric relay today and it fired up 1st time, idled and reved like there was no tomorrow

[DamirGTI 327]

Thanx for all your help. I changed the tachymetric relay today and it fired up 1st time, idled and reved like there was no tomorrow

 

.. so it was the Tachy realy .. odd

 

Damir

[richard 0]

if it is the tachy....then its another sympton to add to its list!