mx5cartalk.com

hi guys,

my nb8a is having coughing issues at the moment at around 2-3k rpm and then again further up in the rev range. i have tested my leads with a multi meter, replaced my plugs and coil pack.

i thought it was my coil pack as i wasnt getting some of the resistance values i should have according to the reading ive done on here. i changed it and it ran better but still far from perfect. when it coughs my innovate wb o2 reads slightly lean for a split second. i.e it will flick from 13.2 to 14.5 or 15 ish

a mate suggested that because i had my car tuned recently, it may have been tuned based on the failing coil pack. is it possible that now i have a new pack everything is a bit out???

my nb8a has 295k on the clock, adaptronic ecu, quads, cams, no cat, hi comp, etc etc. im going to be looking at the cam sensor in the next day or so and i have a nulon fuel system cleaner in at the moment, then a new petrol filter to go in after that.

make sense??

suggestions, comments, thoughts??

thank you in advance :-)

Ben

p.s im haveing serious withdrawals from not driving my beast, so i will apologise in advance if my replies are a bit snappy etc

mmx005 wrote:my nb8a is having coughing issues at the moment at around 2-3k rpm and then again further up in the rev range. i have tested my leads with a multi meter, replaced my plugs and coil pack.

As you probably know similar issues seem fairly common on NB8As for a variety of reasons - know you've tested the plug leads & they seem ok, but unless they're also fairly new & of good quality, I'd at least be trying to borrow a replacement set to see what effect if any it had on the problem.

What that guy ^ said
Try a set of leads from a car that runs fine. Doesn't have to be the proper ones, just as long as they fit for testing.

mmx005 wrote:..a mate suggested that because i had my car tuned recently, it may have been tuned based on the failing coil pack. is it possible that now i have a new pack everything is a bit out???

This mate of yours... reads a lot of Fast Fours, Street Tuner, etc etc doesn't he?
What he said is bunk.
You only need to tune an aftermarket EMS if you're changing the actual setup of the ignition system, ie. installing Coil-On-Plugs, having individual coils feeding each spark plug lead, installing capacitative (spelling)/multiple discharge controllers etc.

Cam sensors are pretty common failures in NB's, so your assumption there might be correct.

Have a good look at every hose for a leaking or loose vacuum hose.

Check ignition timing too.

Are the inlet trumpets open-to-air? or enclosed in an airbox?

Under what load conditions does it have the problem?