Bit of background - MX5 has been smelling a bit fuelly, using oil (1 litre every couple of thousand miles) and feeling a little sluggish. I knew it was slightly overdue for a service, so didnt panic too much.So, I took the plunge and bought new Oil, filter, sparks, fuel filter and a cambelt kit. When I was taking everything out / apart I noticed that cyl 1, 2 and 3 spark plugs were black as anything and that number 4 cyl spark plug was drenched in oil (it was like putting my finger in a small puddle of it!) I figured this would be a leaking cam cover gasket, but after inspecting the old one it doesnt look to have been the case.
Either way - after the service the car started absolutely fine first time and is running okay, but there are a couple of problems i have noticed…
There is a whine coming from somewhere which wasnt there before - Is this just where the new belts (new p/s and aux belt as well as cambelt) need to bed in? I want to say its coming from around the cambelt area, but I know the other 2 belts are more likely to be causing the noise, but still worried… 2) White smoke coming from exhaust - this was there before, but only when it was cold. I left it running for 5 mins, took it for a run and it got upto temperature and it was still doing it 3) The car definately smells like its not burning fuel correctly.
All the parts that I ordered were definately correct Mk1 parts from MX5 Parts, So I know the spark plugs are correct etc. I was thinking possibly bad HT leads giving poor spark causing fuel to be left unburnt? As for the oil in no. 4 cyl, I will have to leave that a week to make sure anything left in theres burnt off and then check the plug to see if its still oily.
Get a 12V LED and check the ECU for fault codes. A faulty O2 sensor can cause overfuelling. Dirty fuel injectors can also cause overfuelling if the pintles are not sealing properly.
New belts can whine. If you have replaced a plain alternator belt with one of the Dayco cogged versions then you don’t need to run the cogged belt as tight as the plain one.
Are you losing/using more oil and/or water recently?
Niggle - thanks for the info, brill as usual. Will check ECU this week and let you know. What would be the best way to check the injectors? Or would I be best off just replacing them? Ive never done that before so not sure how much or little of a job it would be… Will slacken the alternator belt off a tad, because it is the cogged version you speak of.
I had thought possible H/G leak… The car has been using more oil, but not losing coolant. No emulsification anywhere that I could see. I drained all the coolant off and put it back in to the rad when I did the cambelt change, there wasnt any film on top, but some sludgey / oily gunk at the bottom, which was odd, because I thought oil (if it is that) would simply sit on top?
Send/take the injectors to an ASNU franchise holder for checking and cleaning. This will cost ~£50. Do the ECU checks first though and reset the fault codes by pulling the main fuse or disconnecting the battery and then pressing the brake pedal for 30 seconds.
You could probably pick up a set of used injectors for less than £50 but they may not be much better than the ones you already have. One of my injectors had a bad spray pattern and was flowing 20% less than the other three. After 50 minutes of ultrasonic cleaning it was flowing the same as the others and spraying normally. Unfortunately, regular use of Redex in the months before I had the injectors serviced apparently did nothing to help.
I haven’t touched my cogged alternator belt for over a year now since I let the tension off a little. To be sure, run the engine without the PAS/AC belt to establish that the alternator belt is definitely the source of the whine. If you want to do the same for the alternator belt then only run a cold engine, briefly without the alternator belt since the water pump will not be driven.
Thanks niggle. For the sake of a fiver I have got some redex to put through there anyway and am running some shell optimax fuel for a couple of tanks. Just worked my MPG out to be 26!!! Something definately not right, used to average 32MPG no matter how soft or hard I drove. The whine has calmed down a bit now.
Will look into sending the injectors off and report back! Thanks for all advise so far
The ECU fault code check is potentially going to give the biggest win here. A 12V LED probe will cost only pennies (you can get 5 for 2 quid including postage on ebay).
The white smoke has died down after two tanks with double / triple doses of redex, the MPG has gone back up to 28 / 29 which is at least something, still not great, but better than it was. The whining seems to have quietened down, suspect as others suggested it was just a belt settling Im off to Maplin to get some bits on Friday, so will get my little fault code reader then and post up what she says!
Im off to Maplin to get some bits on Friday, so will get my little fault code reader then and post up what she says!