Mazda MX3 Fuel Inj./Lumpy problem

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Thu 7 Jun 2007 01:14
Mazda MX3 Fuel Inj./Lumpy problem - Pheonix
Hi All,

I'm experiencing a few problems with my MX3, which are in some way related to the fuel injection system I believe. Basically, its getting somewhat lumpy in certain rev ranges, and I'm getting real problems with kangarooing when the car shouldn't (read downshifting to 3rd, 2nd). Also certain rev ranges in 2nd and 1st seem to be suceptable to this! I've also had a few instances of it stalling on idle, and twice (I think) the engine revving itself up and down a bit on idle after a drive.

Bear in mind the car does need a service (I'm getting quotes and trying to sort this in the best/most economical way), so things like the fuel filter, air filter could do with replacing. Other pertinent info is that the car was sat for about 6 months before I bought it. However I don't remember having any particular problems with it (although I noticed a slight bit of kangarooing perhaps) when I got it, but it seems to be getting steadily worse.

So, possible problems I've identified (please add to list):

Dirty Fuel Filter
Fuel Supply/Pump problem
Dirty/Blocked/Sticking Injector
Faulty O2 Sensor

Any other things I've missed? I like to be fully informed before I go to a garage (Don't think I'll be able to sort the service myself, nor the problem unfortunately...).

Thanks very much for your help, much appreciated!
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Thu 7 Jun 2007 03:34
Mazda MX3 Fuel Inj./Lumpy problem - Pete M
I've repaired a number of Japanese fuel injection ECUs with simiar problems. There is a problem with the electrolytic capacitors leaking when the units get older. Any electronics technician or TV repair person can do the replacements required. In severe cases the liquid eats away the circuit tracks on the board. If you catch it soon enough replacement of the components (which are easily available through Maplins / RS / Farnell etc. and cost pennies) is sufficient. It may be something else, but it's worth opening the ECU to check. If these cylindrical objects standing up on the circuit board appear to be wet or encrusted with something, or bulging at the end, then replace them all. It's a simple job for any electronics-literate person.

This issue also affects personal computers. My own tally for machines resurrected stands at 7, for friends and family.

HTH
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Thu 7 Jun 2007 09:41
Mazda MX3 Fuel Inj./Lumpy problem - Pheonix
Thanks Pete - good and interesting suggestion. Am in the IT Trade, and have seen this several times, didn't think to think of the car having a problem like that. I'll have a look!
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Fri 8 Jun 2007 16:28
Mazda MX3 Fuel Inj./Lumpy problem - Pheonix
Just for completeness/archival - the car's been in for a service, and the garage think its a split in the air intake which has caused the problem as the engine was unable to adjust the mix properly. They've taped it and it'll need replacing at some point (easy job for me I think! Provided I can get hold of one).

They also noted a few other bits too so thats good to know (even though they're gonna cost me money! Better to be aware and take appropriate actions now!).

Thanks again,
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