Torque Settings for AJP 4.2

[rs200tez]

Hi folks

I've been reading this forum for some time now and have found the topics really intersting and helpful - especially in understanding the level of care and cost of ownership these beautiful cars require.

I decided to take the plunge and buy a Cerb in starmist blue. I have saved enough for a slush fund to take care of servicing and repairs and should be able to top this up every month. I intend to drive the car regularly but it will be mainly a 2nd car. I am based in Bristol.

A month into ownership now and loving every minute - well almost; it was on the back of a trailer on the day I picked it up and again 2 days later!

It's a 4.2 in starmist blue which has been remapped by Austec earlier in the year. It runs 367 lbf.ft but has really poor running on light throttle..

I would like to make it smoother on light throttle so have had a good look around. I have noticed there is a small amount of oil lying on top of the rear most coil pack (think this was due to a previous problem with the dipstick head shearing off, allowing oil to spurt out the top of the dipstick shaft and onto the coilpack). Having a bit of a poke around I noticed the leads dont look particularly new and the coilpacks look like they have been there a while.

I have ordered Magnecor 8.5mm leads, new coil packs and NGK Iridium tipped plugs (might as well replace them while i'm in there). I have 2 questions:

1.) What torque settings should be used for the spark plugs - torque wrench or hand tighten?
2.) Whilst I'm in there, should I change/check anything else?

Any help would be really appreciated.

Thanks

[THE BIG DOG]

Throttle linkage / Ball jonits
Throttle pots.
Worked for me!

[McNasty]

"Running poorly on light throtle", by this do you mean jerky? if so mine does this all the time especialy when trying to keep at a constant speed or the speed limmit. So you just have to put the foot down and she runs very well, traffic permitting of course. Seriously though, there may be nothing wrong if she performs well under load and it is just the fact that she wants to jerk forward and then holds back for a split second before jerking forward again.
mine is a 4.2 as well.

[ridds]

For the plugs you'll need a very slim plug socket. You may even have to get one machined.

Tighten to 25Nm. This is very important according to "Harry" from NGK.

[THE BIG DOG]

McNasty said:

"Running poorly on light throtle", by this do you mean jerky? if so mine does this all the time especialy when trying to keep at a constant speed or the speed limmit. So you just have to put the foot down and she runs very well, traffic permitting of course. Seriously though, there may be nothing wrong if she performs well under load and it is just the fact that she wants to jerk forward and then holds back for a split second before jerking forward again.
mine is a 4.2 as well.

Might be worth having a look at. Have you hooked up to a laptop and had a look? Mine use to suffer from this. Since replacing various bits and bobs she runs as smooth as silk so my head doesn't bop around like a Churchill Dogs in traffic!

[McNasty]

Might be worth having a look at. Have you hooked up to a laptop and had a look? Mine use to suffer from this. Since replacing various bits and bobs she runs as smooth as silk so my head doesn't bop around like a Churchill Dogs in traffic!
[/quote]

Yes, i beleive when she was in for the last MOT due to emisions failure the laptop was hooked up and the appropriate tweeks were carried out. when i first bought her i was told that this was normal and that it is common place with racing engines (albeit detuned for the road).

[rs200tez]

Thanks for the help.

Plant your right foot and it takes off like a rocket and with the Austec mapping, power right the way through the rev range. Much better than some of the others I test drove, but the others did not act jerky on light throttle..

[mikesr]

The throttle linkage is a bad design since the throttle stop is on the off side arm but the pulling is done from the near side arm.

So if there is any play in the linkage when you open the throttle from resting on the stop, the first thing that happens is the near side bank begins to open and the slack in the linkage is taken. Once the slack is taken up, the off side bank begins to open.
This contributes to the kangarooing during start/stop town driving.

Two solutions
One is to put a throttle stop on the near side bank and not use the offside one (slacken it off). That way the spring trying to close the offside bank always keeps the linkage pulled tight despite any slop.

Second is to replace the cheap ball joints on the linkage with some rod ends. Search for 'ondrive' which is where I got mine from

Belt and braces oprtion is to do both of the above.

Obviously the throttle pots will need to be setup after either of these is done.

[THE BIG DOG]

mikesr said:

The throttle linkage is a bad design since the throttle stop is on the off side arm but the pulling is done from the near side arm.

So if there is any play in the linkage when you open the throttle from resting on the stop, the first thing that happens is the near side bank begins to open and the slack in the linkage is taken. Once the slack is taken up, the off side bank begins to open.
This contributes to the kangarooing during start/stop town driving.

Two solutions
One is to put a throttle stop on the near side bank and not use the offside one (slacken it off). That way the spring trying to close the offside bank always keeps the linkage pulled tight despite any slop.

Second is to replace the cheap ball joints on the linkage with some rod ends. Search for 'ondrive' which is where I got mine from

Belt and braces oprtion is to do both of the above.

Obviously the throttle pots will need to be setup after either of these is done.

Same here.
Good dervice from Ondrives. Came next day and fitted like a spot on
Part numbers RAS5 and RAS5L

Edited by THE BIG DOG on Thursday 11th October 17:28

[optimax sniffer]

Hello from another cerb driver in bristol.

The Bristol region of the TVRCC are out for a run into wales on Sunday 21st October. Starting at Severn View Services on the M48 from 08:30hrs for a 09:00hrs start. More details here http://www.tvrcc-bristol.co.uk/web/index.htm 

[rs200tez]

Just thought I'd report back on this work last night; as so many of you offered advice etc.

Ok, just to recap I was hoping to cure a light throttle running problem, where the car seems to misfire and run poorly with light throttle. As soon as you plant the right foot, all goes well and the car pulls like a train right to the rev light.

So I wanted to change:

Coil Packs - Bought the Peugeot/Citreon part as it looks identical.
Ignition Leads - Magnecor Cerbera 4.2 8.5mm competion leads from ACT products
Spark Plugs - NGK Iridium plugs (£6.45 each + VAT!!!)

This is what happened:

1.) Took off scuttle from base of windscreen (had to unplug screen washer hose)+ disconnected battery.
2.) Removed Air ducts and piping. Gently eased the fibreglass section off (where its is sealed with high temp silicone).
3.) Depressureise the fuel system by removing the 20amp fuse in the boot for the pump relay (fuse number 19) then tried starting the car (you will notice the fuel pump does not engage)
4.) ** Important part - draw a diagram of both coil packs and which ignition cable goes where. On my cerbera the two banks are odds and evens (Driver side is evens - starting from the front 8 6 4 2 and the odds are on the passenger side - starting from the front 7 5 3 1).
5.) (I kept a fire extenguisher nearby for this bit) Remove fuel rail by removing 4 x allen bolts. Then you need to gently prise the injectors out (quite tricky) suspend the removed fuel rail to one side, supported with cloth
5.) Remove coil packs by removing 4xallen bolts on each (8 in total). You will notice that the 100amp fuse is mounted on the back of the rear coil pack.
6.) Install and secure with the allen bolts the new coil packs (remembering which serves the odds and evens)
7.) Tried to remove the spark plugs and as warned - this is impossible. Cylinder numbers 3 and 4 are just too difficult. I couldnt get the socket in far enough due to what looks like a cylinder bolt... all the others would have come out ok. I decided that it was best not to mix and match new and old plugs so decided to put all the old ones back in. Anyone who has a socket that will get out all the spark plugs - please give me a shout or let me know where you got it from!!
8.) This bit is the real annoying bit... went to install the new leads and just could not get them on at all. After 30 mins of trying and still no luck in getting even 1 on, decided that there was something wrong. Comparing the new and old leads, I noticed that the hood of the new lead at the spark plug end was 1 cm longer than the old leads. I then did some tests with new and old leads and found that the hood on the new leads is too long and does not allow you to push home onto the spark plug... not happy. Checked the box the leads came in and it does say Cerbera 4.2 1995 + so I dont know what is going on there! Bought the leads from ACT..
9.)Put the old leads back on
10.) Installed the fuel rail... nightmare to do without bending the injectors.
11.) Replaced the air intakes and sealed with high temp sealant
12.) Reconnected battery - held remote button down for 14 seconds and alarm re-engaged
13.) Replaced scuttle cover and windscreen washer pipe.
14.) Inserted 20amp fuse
15.) Rechecked everything!
16.) Got fire extenguisher ready
17.) Fired up 1st time

Result.....

Light throttle running - slightly better! Still not what I want.
Hands covered in blood - apply copious amounts of germolene.
Neighbours - not happy - finished at 00:00!
Caught Pneumonia

But.... I know alot more about Cerbera's and I'm pleased to say that it did start first time. Also thanks to my helper - James Copp-Taylor!

Any thoughts, advice, general piss taking over my experience more than welcome!!

Thanks for your help.

[vectrolosys]

Hello,

I was James's willing helper during this job. Getting my hands dirty and being found under the bonnet of a car are things I tend to enjoy the most. When I had the chance to help repair a TVR, I jumped at the chance, what petrolhead wouldn't!.

Having worked on some tight engine bays (V6 Omega, Vectra etc) the amount of space that greeted me in the Cerbs bay was quite refreshing!.

After replacing the coil packs, cleaning up the area etc, I noted some areas which I feel may be contributing slightly to the lumpy running at part throttle.

An engine breather hose, which connects to the right hand plenum into a gauze filter, was badly crushed, flimsy and generally cracked, I feel this may contribute to the poor running, as air leaks won't do any cars running any good, this is something on the list to replace, as well as soaking the gauze filter in some gunk, or similar.

I noted some hairline fractures on the fibreglass plenum bits, I guess these could also contribute to potential airleaks, again something to consider repairing or replacing.

I was suprised to see that the exhaust manifolds (which were very attractive pieces of metal, and efficient looking) were not wrapped, would wrapping the manifolds in exhaust bandage help? My reason for asking, is the HT leads run above these (cable tied to another heat source, a coolant pipe) and anything to reduce the heat near them would surely help the situation.

On the whole, I look forward to working on the car again, but second RS200tez's remarks on the plug socket, a thin walled item would definately be an advantage!.

James

[Steve_T]

I'd suggest you give ACT a call. I'm sure they'll sort the lead situation out for you.

[SimonSparrow]

mikesr said:

The throttle linkage is a bad design since the throttle stop is on the off side arm but the pulling is done from the near side arm.

So if there is any play in the linkage when you open the throttle from resting on the stop, the first thing that happens is the near side bank begins to open and the slack in the linkage is taken. Once the slack is taken up, the off side bank begins to open.
This contributes to the kangarooing during start/stop town driving.

Two solutions
One is to put a throttle stop on the near side bank and not use the offside one (slacken it off). That way the spring trying to close the offside bank always keeps the linkage pulled tight despite any slop.

Second is to replace the cheap ball joints on the linkage with some rod ends. Search for 'ondrive' which is where I got mine from

Belt and braces oprtion is to do both of the above.

Obviously the throttle pots will need to be setup after either of these is done.

Great idea about the throttle stop position. I have rod ends on mine, but even they have a little bit of play. Do you have any pictures of your new throttle stop Mike?

[mikesr]

SimonSparrow said:

Great idea about the throttle stop position. I have rod ends on mine, but even they have a little bit of play. Do you have any pictures of your new throttle stop Mike?

Got some pics on the laptop. I''ll post them up over the weekend.

I've probably still got the card template I used to cut and fold the aluminium sheet

Although I'm looking to create a new design that bolts onto the intake rather than the throttle cable bracket. (But don't hold your breath waiting for a redesign, I've got an oil catch tank thats nearing its first birthday and I still haven't fitted that)

[SimonSparrow]

mikesr said:

SimonSparrow said:

Great idea about the throttle stop position. I have rod ends on mine, but even they have a little bit of play. Do you have any pictures of your new throttle stop Mike?

Got some pics on the laptop. I''ll post them up over the weekend.

I've probably still got the card template I used to cut and fold the aluminium sheet

Although I'm looking to create a new design that bolts onto the intake rather than the throttle cable bracket. (But don't hold your breath waiting for a redesign, I've got an oil catch tank thats nearing its first birthday and I still haven't fitted that)

Thanks, know what you mean, I think my oil catch tank project is older than yours! I was pondering about making a throttle stop using the big allen grub screw that is in the end of the throttle body.

[mikesr]

I was looking at trying to bolt a stop to the top of the manifold with the tapped hole that isn't used on the nearside manifold. IIRC its got a roll pin to hold a spring on the offside manifold.

It would keep the throttle stop away from the throttle arm itself. The current design sits vertically alongside the throttle arm bolted to the cable bracket.

[Tanguero]

Rather than removing the fuel rail from the intake trumpets, I found it far easier to remove the whole assembly as one piece. There are a row of hex cap head set screws that hold the intakes to the block. Undo those and disconnect the throttle cable and fuel lines and the whole thing comes away with its spacers. Gives you a lot more room to work and saves the pain of getting the injectors back in. Just stuff a bit of cloth in the hole above each valve before you drop anything into the holes.

I am surprised you had problems getting the plugs out - on my 4.2 the same socket worked fine for all of them. The pair nearest the cockpit I had to put the socket on the plug with fingertips then use a UJ on an extension to turn it. If it helps I can measure the external dimensions of the socket I used and post them tomorow.


I also got the same leads from ACT, and had quite a strugle getting them seated until I lubricated the inside of the boots with a little silicone grease, then they popped right on.

Altogether it made a massive difference to the way mine runs so it is worth persevering with the leads and plugs.

[Mr M]

Just for the record. 4.2 owner here. Car used to have "Green filters" with an Austec map. Original induction pipes now back to normal and drives far better. Car is fantastic overall but is not that smooth through 1st and 2nd, especially 2nd. Maybe an original map would sort this out.

[vectrolosys]

Tanguero said:

Rather than removing the fuel rail from the intake trumpets, I found it far easier to remove the whole assembly as one piece. There are a row of hex cap head set screws that hold the intakes to the block. Undo those and disconnect the throttle cable and fuel lines and the whole thing comes away with its spacers. Gives you a lot more room to work and saves the pain of getting the injectors back in. Just stuff a bit of cloth in the hole above each valve before you drop anything into the holes.

I am surprised you had problems getting the plugs out - on my 4.2 the same socket worked fine for all of them. The pair nearest the cockpit I had to put the socket on the plug with fingertips then use a UJ on an extension to turn it. If it helps I can measure the external dimensions of the socket I used and post them tomorow.


I also got the same leads from ACT, and had quite a strugle getting them seated until I lubricated the inside of the boots with a little silicone grease, then they popped right on.

Altogether it made a massive difference to the way mine runs so it is worth persevering with the leads and plugs.

Hello,

I'd be interested to see the measurements. The toolkit we used (my well specced Halfords affair) contained a plug socket that was the correct size for the plugs, but getting them into the plug holes was a serious squeeze, to the point where we thought we'd not be able to extract the tool from the head!!.

The Silicone trick is one I should have thought of to be honest, when the cars owner returns from holiday, it's certainly something that will be worth trying.

To be honest, getting the fuel rail back on was not a huge nightmare and took five minutes tops. Can see how removing the entire assembly would improve access, but compared to some of the engines I've worked on, the space available here was postively luxurious .

James