running problems with sag

[clive f]

have given the sag a service, before I started I noticed the tickover had dropped to 650 700rpm, and on using a laser temperature reader found that on tickover the exhaust primary from no1 cylinder a lot lower than the others, but with the revs increased slightly then no1 temps would be the same as the others, so its missfiring at low rpm on no 1 pot.

so, after checking and adjusting shims, a bit miffed as all of the exhaust clearances were 7-8thou instead of the 12-13thou required, and all of the inlets were down to 4thou, 2 down on what they should be,this was supposedly last done during its 12k service, 7k miles/ 18 months ago under previous ownership.

anyway, on putting it back together I decided to treat it to a new set of standard ht leads, plus a new bosche coil in an attempt to cure the earlier missfire problem, along with a new set of plugs with gaps set at 32thou.

fired it up this morning, tickover still down, so took here for a spin to warm it all up, drives nice, but, if you are up on the revs and in the right gear she picks up nice and cleanly, however, crawl along at 1500rpm in say third and put your foot down she starts miss firing, then clears and picks up as the revs increase, so something still not right, temperature reading on no1 exh still lower than others on low rpm, so any ideas on what this can be?

have checked in graham`s manual, only thing not checked is loose throttle pots, front one is tight, waiting for it to cool down to check the rear one.
as for injectors, the old spark plugs that came out were all the same colour, no indication there.

[Don1]

(This could well be me exposing my mechanical lack of knowledge, BUT...)... if you've removed an electrical and clearance potential cause of issue, aren't you then looking at mechanical?

(Sorry if this is the case, fingers crossed it is the pots)

[kevin63]

I'm only clutch at straws Clive, but have you had an airflow meter on it to check the throttle body adjustment.

[Mattt]

Can you plug into the ECU and check the readings there?

[clive f]

Not far off there kev, just had a quick chat with jason from str8six, basically its proably down to checking the air, balancing throttle bodies ect, makes sense, I checked all this when I first got the car, went to have a go this morning and had total memory loss on what I had to do............must be old age creeping up again

to add yes had laptop in, and adaptives were down slightly on front 3 pots, so will now recheck and get it all set up again............properly.

[Don1]

Fingers crossed!

[bobd]

Clive
had this on the Tamora, couldnt get it balanced at low revs and no 1 pot was ever so slightly pulling more fuel at idle.
There is a small plastic switch block (potentiometer I think) on the end of the throttle linkage next to No1 cylinder intake. Remove it and then flat file the side of the plastic facing the linkage. This will prevent it sticking as when it does as its ever so slightly you can hardly notice. This proved the case on mine even with air flow meters on the inlets.
worth a try as it took a good hour to find the problem , but with a light file it was job done
good luck

[clive f]

thanks for the tip bob, I`ll have a look.

[SpeedBuzz]

I had a missfire on mine recently which was getting very hard to pinpoint.
My local garage had real trouble getting the throttle bodies set up and thought air was leaking in via the manifold.
Anyway to cut a long story short I took it up to Dom at TVR Power who had a look and found an error straight away, apparently there was an electrical earth mod on the Sagaris which went out to the dealers and mine was wired up incorrectly by a previous dealer.
Once rectified we could set up the engine and get her balanced properly and allowed them to find the missfire which i believe was either a duff plug or the coil.
Anyway i can only conclude that this wiring error must have been like it for a while as the difference was quite noticable and now a very good stable tick over even when cold.
I drove her back home with a big Grin as she was running the best ever.

[clive f]

with the laptop connected I have found that the lambda sensor for 123 is on the blink, the voltage not fluctuating from 9 to zero, so have ordered another and then with balance throttles again and set up.

[Targarama]

Might not be related, but there was a mod to add a better earth to the lambdas. Jason knows all about it.