Had an issue that has rendered the car off the road for a few weeks now.
It is my girlfriend’s car, a mk2 Jasper Conran (2000) and the problem began with it running “lumpy”. When I was in the car I identified as a misfire.
The misfire would usually occur when up in 4th gear and was usually one cylinder, but sometimes felt like two. Not necessarily under load, but usually a few minutes into the journey. It would then stay for a few minutes until you went slow enough to get down to second where it eventually sort of stops (but not always). You really had to nurse it home. There was also a smell of burning plastic from under the bonnet.
The car was due a service, so changed the sparks, oil and filters - no change.
We then replaced the HT leads - no change.
We then had the code reading LED arrive and pulled out the 1633 Battery overcharge code (the check engine light bulb has gone in the dash so we did not know if it was on or not). Unfortunately my multi-meter had died and wouldn’t let me check this.
I ordered a second hand coil-pack in case it was at fault, new ones are too expensive! On the old coil-pack cylinder one had a dirty contact point, so i was hopeful the new pack would sort the issue - alas still no improvement.
Today I bought a new multi-meter and measured the voltages. The battery was about 12.4V when the car was off, and rose to 14.9V as soon as the car was started. Under a very light rev, this rose up to 15V.
These values appear too high and given more rev’s/load I would imagine the voltage would go higher. This in my opinion probably genuinely caused the overcharge code, the burning smell could also be coming from the alternator although the exact source is hard to identify.
Before we shell out to replace the alternator, does anybody have any other suggestions, or has anyone heard of an overcharge causing misfires like we are experiencing?
Kinda sounds like alternator alright.We probably have good used one .Also did you check the ecu, under passengers feet, with metal plate over it.If ecu gets damp/wet this can cause all sorts of issues incl not charging/overcharging etc amongst hundreds of other issues.We might have ecu but check for dampness firstly.Lift the carpets as they may feel dry on top but could be 1inch of water underneath
Agree with above - check the ecu. Alternator is regulated by the ecu and is overcharging so not regulated correctly. Also more than a coincidence that you have the two completely separate issues.
The charge rate for the MK2 should be around 14.5 - 14.8 volts. Anything above this is overcharging as correctly picked up by the diagnostics.
Once exposed, any water damage to the ecu will be very obvious.
Good advice there, are the passenger carpets damp of wet? Always a clue to start with. Also a question of “Are you aware of the clearing the drain tubes issue?” Usually the cause of wet or damp carpets, and worst case - damp or wet ECU’s. The Mk2 voltage regulator is not part of the alternator, it’s done by the ECU.
ECU’s aren’t cheap as chips, so if it’s wet or damp - try drying it out with a hair dryer (not too close, or you’ll damage the components) - but the trick is removing the steel cover plate, which has special security screws which are a problem - there is a cure if you need it. - You have to chisel a slot in the head so you can remove it with a blade screwdriver. Once dry, replace the steel cover plate, but make sure you seal it down with silicone grease to prevent further water damage
Clearing drain tubes - best tool is a plastic covered wire as used by Grandma to hold up net curtains, - you can still buy from most curtain shops and good hardware stores. Where the soft top main hinge is located next to the seat belt tower, you’ll find a recessed hole, where water drains from the top when it’s raining (often in this country) and drops through the tube down under the car. Get a good length of curtain wire, and fish it down the hole till it appears under the car, where if the tube is blocked the debris should come out below. Don’t get too vigorous, or you’ll dislodge the rubber flap where the drain ends - this stops road noise coming back up the tube and adding noise inside the car. If the drain get’s blocked, then you will have wet carpets, and eventually a problem with wet ECU’s.
We are aware of the drain holes and have always kept them clear, even so there is always condensation inside the boot which ends up in the spare wheel well!
I have just been and pulled back the carpet which is quite tricky as it appears a previous owner has re-carpeted it over the original stuff. I didn’t take it right back but enough to put my hand down under to check for moisture.
I searched online for a picture of somebody else getting to the ECU to work out where it was, and from the feel of it there was no moisture down there, although I didn’t remove the kick-plate. What a stupid place to put the ECU!
Is it worth my time trying to get it out fully and giving it a look over if it feel dry? MX5 123if you have an alternator we could purchase to try could you PM me the details please?