Hello all,
This is my first post and wonder if anyone could help me as my problem is leading to 1.2 pug 106's overtaking me and it's driving me mad. !!!
I have had 10 happy months with my bargain S40 t4, i love it in every way, especially the price i paid for it...
The car i bought had 122k with a newly fitted engine with 60 k, the guy i bought it off was a volvo mechanic, and had replaced everything on it body wise, proper minter..
The only problem that it had was it was missing under heavy load ie on motorway booting it etc, turned out to be a split coil pack.... so replaced and everything seemed fine except it didnt seem as fast or the turbo seemed not as vicious (compared to my Saab 900 t and my Skoda Octavia VRS) as id expected.
So i got a dawes valve and fitted a turbo gauge, the gauge without the dawes was running between 0.6 n 0.7 bar which obviously seemed a little under, so i fitted the dawes valve and cranked it up so was pushing 0.9 to 1.1 bar, i started thinking he'd fitted B2024T2 engine untill i did a video'd test run to 60 then to 100 mph, with the dawes on pushing 0.9 bar it hit 0 - 60 in 6 secs and to a 100 in abt 13, so came to the conclusion my cheap gauge was in-accurate and lately its been sticking and getting frozen up. I also fitted an induction kit.
The problem im having is that it keeps missing still under load.
I had a mechanic change my mobil oil for me and he poured it all over the engine cover about 6 months ago, he cleaned it all up, but still i had to clean it regularily when it started missing badly and all would seem ok.
I changed all the plugs twice in 10k, recently changed plug leads, everytime i took the electrics ie plugs, coils etc it worked fine then 50 miles in it would start missing under load agn, the coils are fine (plugs when removed are norm colour).. It definitely feels like an electrical problem and yet ive recently noticed it seems to be only between 2 - 4/5 k revs after that it goes like a rocket and it's also starting to run a little lumpy on tickover, like one of the cylinders isnt getting all the power it needs.
I changed the electrical wires that feed the coil packs as the originals looked old and wires were exposed on the female fittings. Was marginally better for a while..
I think that ive threaded the bolt holes that hold the coil packs in place, but they are still fairly secure i think...
The thing thats really confusing me is why when i take everything out and clean it all up it runs fine for a while, when i wiggle all the wires that also improves it for a while... I'm at my witts end now though as ive replaced everthing i can on the ignition side and yet im still positive thats whats causing the problem.... I dont know what else to try.... The dawes valve has been taken off but that didnt improve anything.......
Just to clarify theres no smoke (engine truly is mint).
The cam cover reads as the engine being the T2 variation with vvt, the original 99 lump wasnt vvt.
Changing petrol to high octane makes no difference.
The fuel pump is quiet and makes no diff if tank is full.
Sorry for my waffle but wanted to get down as much as possible.
This car is my baby, i painted all the trim up got new wheels and im so proud of it but this elec prob is marring my experience and im considering getting something else,i dont want to cause i know ive gotta good motor but im getting fed up now,i'm sure its something fairly simple..
If anybody can give me some fresh ideas i would be so grateful.... Cheers all !!!

 

My S40 was missing under high boost (around 12 or so psi) turned out to be the alternator, wasn't supplying enough to the battery, so the spark wasn't hot enough.

But with mine there was other symptoms of the faulty alternator as well.....

You might also want to check your plugs, with higher boost levels you want to make sure that your gaps are at the lower end of the range

 

Cheers bud, think its defo the coil packs although neither are cracked one was bought second hand and it looks old. Thx for your reply..