borat52

I've just been out in my 1993 WRX after upping the boost to about 1.2 bar (mapped for) and I'm getting quite a nasty hesitation at 4.5 - 5k rpm. Is this likely to be coil packs or spark plugs? Had a new set of plugs 12 months ago but not sure if they were gapped correctly. No hesitation if I accelerate a little less vigorously but if I give it full boost it seems to come right off power for a moment at these revs, happens in 2nd, 3rd and 4th.
Any advice appreciated.
thanks
will

skyline gtr v

Sounds like coil pack same think happend to mine got it changed and not a bother.

Scott.T

iTrader: (2)

Coil packs
pull them out, take the rubber boots off and check for cracks.
I'm hoping to get an image up on my website Frequently Asked Questions soon, so people know what to look for

you can wrap several layers of insulation tape around the ends, which may stop the big hesitations. But it it not a full solution as you will probably be loosing power due to a weak spark.

EDITTED to Say : here you go....just found this amongst my emails. This is worse case, but gives you an idea of where the cracks form

borat52

Cheers Scott,
Fountain of knowledge as per usual!
I'll pull them out this evening and check them, suppose it can't hurt to check the plugs for the correct gap at the same time.
Much appreciated.
Will

borat52

I've just got on the case for a set of bosch 723 remote ignition coils, but understand I need some HT leads for these. Does anybody know what HT leads are required?
cheers
Will

Scott.T

iTrader: (2)

IMHO you would be better to get a set of coil packs from JPS for £200.
The MEC's are supposed to be no better, plus you need leads and have to mess about finding mounting locations for the coils....

borat52

I've just pulled the first one out over lunch and it looks like someone has already replaced the coil packs, was in absolute mint condition, no cracks, looked very clean. Took the plug out and found it was gapped to 1.1mm. I am going to try regapping at 0.7mm and see if it solves the problem. If I do find a cracked coil I'll be going JPS as advised through.
thanks
will

borat52

All other plugs/coils now checked, other plugs gapped correctly and coils all mint. Took it out for a quick blast and problem has gone completely. I think it was either the gap on the first plug I took out or theres a possibility the plug was loose. I was messing about in there with a socket trying to get it out before I unearthed my sparkplug attatchment and it was loose as soon as the spark plug attatchment went on it, could have loosened it with the socket or could have been the culprit. Either way problem solved so I'm now a happy man, just the clips on the FMIC to sort out and then I can get a power run in.
Cheers chaps,
Will

Scott.T

iTrader: (2)

Glad it's all sorted...bloody coil packs and porley gapped plugs are a big issue when running higher boost, and I've forgotten how many people I've metioned it too when they fit a remapped chip hence the reason for the new website FAQ.

borat52

Well I think I spoke too soon on this one. Regapped plugs and took it for a few blasts down the dual carriageway and it was fine. I then went out the next day and coming off a roundabout in 3rd I had the most sever hesitation I have ever had. Ordered 4 new coil packs and fitted them today. Went out this evening and floored it off a roundabout in 3rd from about 3krpm to 6krpm and all was fine, then down the road I was cruising in 5th at 80 and decided to give it another blast and it happened again, 4.5krpm, big hesitation. So the problem remains.

I have a knocklink installed and it was on the first green when this happened (its set as sensitive as possible and I have seen oranges with spirited driving previously) so I'm pretty sure its not leaning out. But what else could it be? My next step would be to replace the plugs with new ones, but could there be any other possibilities.

As I said its not happening all of the time, can't be coil packs now and once its missed a beat it pulls really hard all the way to the redline.
Any suggestions welcome.

Scott.T

iTrader: (2)

sounds like a mild case of fuel cut.
Do you still have the restrictor in the boost control solenoid return pipe ?
If you don't then fit one
If you do then may be worth lengthening the actuator rod by 1 turn or reducing the size of the hole in the restrictor mentioned above.

borat52

I dont think it can be this,as I'm running a dawes device to control boost, and have a ESL chip with fuel cut removed. (The restrictor in the pipe still though)

Sc0oby

check for clog fuel filters. these can sometimes be the culprit

robf

Reminds me that I have a new set of Bosch coils that I need to put in the for sale forum. If interested, send me a PM.

-Rob