10 replies to this topic

[TimNeal]

Hi guys,

Ive just rebuilt my MPi and have fitted the Kent274MD injected cam, new LCB exhaust retaining Cat and changed to a 3:2 diff. Car has had from new the MED supplied "Works Head" with K&N filter and 1:5 rollers.

Steve at MED reccomended not to run the 1:5 as the cam would do the required lift etc and the EMEs system would struggle with any more.

I have the engine back in and running, Ive done the running in of the Cam per CalverST tech pages and have now tried to run in as Keith suggests by taking the car in 3rd gear upto 2200-2400 rpm and then flat foot the gas pedal for 10 seconds. 

Every time I do this the car surges and jerks and cuts out. It restarts fine and will drive, but try it again and same thing coughs and farts. 

Thinking the issue is fueling Ive stripped the fuel rail and injectors, which has already been stripped and cleaned/tested. Fitted new o-rings and silicon greased, reintalled and it seem to go fine. After getting the WOF (MOT) sorted I had another go at bedding in rings and it did it again.

Ive seen a few older thread on here discussing similar issues, and debate over the "power boost valve"  etc which didn't seem to come to a conclusion. 

Has anyone else fitted this cam or similar and had similar results? And how did you resolve it ?

Im based in New Zealand and own one of only 5/6 English Mpi cars here. most being JDM SPis, so theres not a huge base of information to work with so any qualified soloutions greatfully accepted.

Thanks Tim

[Midas Mk1]

I’d be going stand-alone tb and ecu next, that way you can get the tune calibrated perfectly for your spec, running at optimum.

Mems caused me a headache even in a fairly standard tune.

[craig 1010cc]

sounds like it should be a cracking engine when its issues are sorted.

 

Does it do the same thing if you bring the throttle in more gently (still to 100% open, but over a couple of seconds)?

 

I didn't have this issue with my old Si, but what I did have and would be worth checking is if the inlet manifold is bolted up tight. I fitted a stainless LCB and the flange thickness was different and caused the inlet to work lose after a short time (to the point you could wobble it by hand) and that would cause a big air leak which could be what yours is struggling to compensate for with sudden wide open throttle.

[TimNeal]

sounds like it should be a cracking engine when its issues are sorted.

 

Does it do the same thing if you bring the throttle in more gently (still to 100% open, but over a couple of seconds)?

 

I didn't have this issue with my old Si, but what I did have and would be worth checking is if the inlet manifold is bolted up tight. I fitted a stainless LCB and the flange thickness was different and caused the inlet to work lose after a short time (to the point you could wobble it by hand) and that would cause a big air leak which could be what yours is struggling to compensate for with sudden wide open throttle.

During the install process I set up the manifold+LCB to a spare head on the bench and checked thickness. Everything was correct and would tighten up. Ive been caught in that trap before and having to weld on spacers to the washers. 

If I accelerate normally it appears to go past 3500rpm no issue. But at this stage on a new un-run-in engine Im hesitant to do any mileage.

Im wondering if I might need to remove the O2/Lambda. I fitted a new one supplied locally thats not a Bosche and I see in other threads that off brand isn't a good idea. So Ive just been and borrowed a O2 Socket and will swap it over for the original one. 
WIsh I'd read that bit before bolting it all in place!

I'll get it sorted this morning and let you know.

Edited by TimNeal, 09 February 2023 - 08:36 PM.

[TimNeal]

I’d be going stand-alone tb and ecu next, that way you can get the tune calibrated perfectly for your spec, running at optimum.

Mems caused me a headache even in a fairly standard tune.

Not really an option, I don't race this car, its my cruiser so tinkering with computers isn't something Im interested in doing.

My race cars "old school" like the owner, with a 45dcoe which Im much more "a-Tuned" to 

[TimNeal]

removed the non-bosche O2 sensor, replaced with the original O2 sensor.
Checked manifold, no indication of an air-leak , quick squirt of ether doesn't alter revs etc which is usually a sign its pulling in air. 

Still spluttering/missing and dieing but now at 4000rpm. 

 

she will run through into 4th and pull if gentle acceleration. 

Im going to pop round to see a guy whose been reccomended as good with computer stuff, usually he's a Skyline man and drifts, but I won't hold it (to much ) against him that he doesn't head out into the forest to get the car sideways at 100mph. He is under 35 so probably had a sheltered life *wink wink*

[Quinlan minor]

Given the circumstances in which the problem occurs, I would closely examine the HT system, first.

[pete l]

sounds ignition related to me too. with the throttle open, all the air etc. is "blowing out" the weak spark.

 

can you borrow a coil pack from someone ?

Edited by pete l, 10 February 2023 - 07:47 AM.

[TimNeal]

sounds ignition related to me too. with the throttle open, all the air etc. is "blowing out" the weak spark.

 

can you borrow a coil pack from someone ?

I might be able to track down one from a Japanese SPI to borrow. I'll call him in the AM

[TimNeal]

Given the circumstances in which the problem occurs, I would closely examine the HT system, first.

I'll pop the leads off and check them, 

I popped round to see the clever young fella who was reccomended to me and he looked at me and said "it has a computer" I opened the bonnet and showed him, he was shocked to say the least and all he could say was that it was way above his pay grade.
Might see a guy on Sunday who deals a lot with MGs  and he races an early MGF which runs the MEMs system so he might have some ideas also.

[TimNeal]

Guys, what can I say!

Pete and Quinan where on the money. Ignition fault.

Checked the coil, all good and multimeter check showed it was right, so cleaned all contacts with a product called "Deoxite" which I use for cleaning hifi amp pots, all the leads, sockets and pulled out the plugs and had to reset the gaps as I'd set them at the std 25thou but checked and the book says 85mm on the injected. So a little tight.

Fired her up, drove around the corner to get her warm then hit the straigh country road and floored it in 3rd and she pulled straight round to 5000rpm no hesitation.

So running in today, oil change tonight and off to british car day in Wellington tomorrow. 

Thanks Guys you are "the bomb" as the nephews all say