Engine "chugging" - all power then no power

[CMF_Bob Flemming]

Hi. Please go easy as this is my first post and I desperately need your help. I have read so many pages and suggested solutions that I'm only posting now as I'm out of ideas.

I purchased a 1999 K11 Micra as a "sold as seen" on Ebay and have had nothing but trouble with it. The engine will run fine one minute giving good power and response and then it will suddenly "chug" or "judder" - skipping from having power to having none what so ever. When it does this it really struggles to tick over and will usually stall. There seems to be no common cause though - sometimes its hot, sometimes cold. Sometimes it won't even tick over at initial start up. Other times it will run fine for an entire journey or 30+ miles.

I have already replaced the following components in an attempt to remedy the fault - HT Leads, Dizzy cap (x2), Dizzy (x3), complete throttle body change including three combinations of sensors (Air Flow Meter, Throttle Potentiometer etc), air filter and battery. I have also checked the fuel pump is in full working order.

Engine management light does not illuminate when the fault occurs, only if the engine stalls.

Any suggestions? You help and advice is humbly accepted.

 

[CMF_frank2]

hi bob

it sounds like a dodgy electrical connection to me, i had a similar problem with the plug on the maf, and another with the ecu connector, and the injector fuse holder (near the battery) is prone

frank

 

[CMF_tez]

Hi Bob,

another thing that I thought of is vacuum leaks, are there any cracks in the pipework between the brake booster and inlet manifold? Also might be worth checking the brake boster itself to be sure it's not leaking air.

Other than that, changing the fuel filter may help, if it's blocked you will have the symptoms you described, although generally its not intermittent.

As Frank suggested, check for electrical faults, I'd tend to focus on fuel related areas, ie. fuel pump wiring and fuses, injector wiring/fuses etc.

Goo luck

 

[CMF_Bob Flemming]

Thanks so much for your quick responses and good advice.

Upon my return home today I found that my dad had arranged for an old friend, who is also an auto electrician to come over. He brought a diagnostic reader system with him and within minutes of plugging it in it reported a fault on the MAF sensor.

It looks like the one I'd used to replace my origional was also faulty! The chances of that eh, two faulty MAFs in a row!

After he left I replaced the unit with another spare I had raided from a scrap yard and already soldered into a second throttle body. Sadly he'd left before the change over was complete so we're not sure if this MAF is faulty or not either. However, we've had the car running for the past hour with no problems.

IF the problem does rear its head again he suggested getting a completely new MAF. I've already found these on EBay.

So, watch this space. I'll run it for a while and see what happens. I'll keep everyone posted.

Again, many thanks for all your help and advice.

PS Forgot to say in my first post that I've already replaced the fuel filter.