Hi guys, my mondial qv has developed a strange issue where it’s down on power and won’t rev, it idles fine and sometimes revs well when parked but as soon as it’s driven it has a 3/4k limit and misfires like mad has anyone got any ideas? I’ve already done the fuel pump and a new set of plug, I’ve also done rotors (as they were the cheapest) but don’t want to start buying leads/caps if they’re not needed. I was thinking maybe coils but need a second opinion thanks
Your location implies that it's a euro version, but please confirm the actual version -- euro or US, and/or post a picture of the engine bay that includes the fuel distributor area.
Certainly wouldn't hurt to follow Guido's thought and first confirm/deny if the airflow metering plate (and plunger) moves smoothly and easily in both directions once you've bled off any fuel pressure (by, for example, cracking the cold start injector connection open wrapped with a rag to catch the spray) -- doesn't require any special equipment. This is a case where a Shop has a big advantage over a DIYer as they would probably have access to another coil and another Digiplex ECU to swap parts around to see if it makes any difference or not. If you can confirm that the ignition system is OK, the next area is the CIS system (which on your euro version is a completely hydraulic-mechanical system with no electrical control) so measuring the various pressures (regulated supply, cold control, and warm control) are the diagnostic steps.
Could also be lack of flow from the fuel pump. There is a procedure to check it out of the return fuel line.
I’ve replaced the fuel pump as I had to remove the tank to do the sender so did it at the same time, I haven’t, however, done the fuel filter, do you think this could cause it? I did wonder if it was fuel but started to think it might be an ignition issue. where is the filter on the distributor please? I’ve not had much experience with fuel distributors as I’ve usually tried to leave them alone
Not sure about your particular car, but on the k-jet you usually have got an "in tank" mesh screen in the fuel pickups that allows to filter out the bigest debris before they get in the pump. This mesh screen is often neglcted which leads to pump failure. After the pump you've got a thin Bosch filter (the one usually replaced during maintenance). Then on the fuel inlet of the distributor you may (on the older k-jet) have a mesh screen that you can see inside the port. They are several exit from the distributor, the one in the centre (i.e not the one going to the injectors) goes to the WUR. In the inlet port of the WUR you've got a stack of 3 mesh screens that often gets clogged. This one is a pain to clean-up. So that's up to 4 filters to check. Your intank screen should be clean, as you've replaced the tank. I doubt this is the WUR screen as your mixture would be totally out of place on the whole rev range. A set of k-jet test gauge ($80 on ebay.de for an accurate one) would allow to validate my assumption. Assuming you had to change the tanks, the interior of the damaged tank was probably corroded and debris found their way in the thin filter that is after the pump. So I would first change this filter. Bosch filters are nice, but the Mahle equivalent (ref EFG22) is slightly bigger (so can swallow more crude) and so cheap that I replace the filter twice. A first "sacrificial" filter is used to restart the car and collect whatever is in the system. Shortly after I just replace it again.
Alex, the main fuel filter is located on the rh side of the engine bay: Image Unavailable, Please Login I just opened up a filter after 8'000 mls of usage to see how it looks inside. This is the paper filter unrolled and unfolded: Image Unavailable, Please Login It seems to do its job. It also seems that the fuel is not as clean as I wished. The fuel distributor inlet filter is right here: Image Unavailable, Please Login And looks like that: Image Unavailable, Please Login The WUR inlet filter his below the banjo fitting (and you can see the problem): Image Unavailable, Please Login My car first displayed full throttle issues which them became medium throttle issues - it would essentially run fine at constant speed but did not want to pick up any revs. Starting was no issue. It happened twice recently, and both time it was caused by a dirty inlet filter.
Thank you, I’ve ordered a fuel filter, I’ll do all three of those and see what I can find, hopefully that’s it as that doesn’t seem too bad of a job I’ll let you know how I get on
The above filter seems to be clogged by black rubber from the hoses. The original cohline hoses do not like the new blends of gazoline. Cohpro even reluctantly sell this particular hose except for "concourse"... If the wur is clogged, best solution is to open it remove the gaskets, clean it with acetone and use compress air from the inside in the two small holes in the black disk.This pushes the crude out of the screens. Image Unavailable, Please Login Image Unavailable, Please Login
Hi everyone, today was the day, new fuel filter and cleaning all the above, filter coming off was filthy so needed doing, once done it ran perfectly and revving well, on the drive home, went back to misfiring. weirdly, if I turn it off and on again; it’ll rev fine again for a while then back to a weird 3k redline Any ideas on what to try next? Thanks
Sounds typical of a rusting gas tank. Flakes clog the pickup or the gas filter. Flakes drop back when the fuel pump vacuum stops sucking them up (engine stopped). Then pulled vacuum up when pump back on.
It’s weird, when I took the tank out to change the fuel level sender it actually looked rather clean, it’s had a new pump and filter. does it sound fuel related? Or do you think I maybe should look at ignition?
How long is the "off" time? Also, does the trouble come back (and how soon after restarting)? Yes (if the problem repeatedly occurs when the ignition system heats up and heals after the ignition cools off, and then reoccurs again if the ignition heats up again, etc.).
It was off for less than a second, it was switch off and then straight back on and revved fine, then went to 3k redline again, turned it off for slightly longer (5mins) and hasn’t gone back yet but I’m at home revving stationary at the moment as it’s raining. it does smell very rich which is new (burn your eyes rich)
Sorry I am unfamiliar with the fuel tank intake. Does it have a sock over the end? If you pull it out again, you might see some debris on it. Otherwise, yep, things such as coils having erratic behavior us also common. The usual test is to swap out coils with known good ones -- something not practical for DIYers.
That’s what’s worrying me, thinking I might be going down the wrong route, any way to check coils without buying new ones?
Just disconnect the cold start injector and see if this cures the issue. More probably you've cleaned up the system, so the wur could be now less restricitve, i.e lower control pressure, i.e richer when hot. So you would have to check control and system pressure. Also did you clean the fuel pickups in the tank? Image Unavailable, Please Login
Stupidly I didn’t check the pickups, removing the tank was such a job in itself I completely missed that, I’ll have to run the tank down and remove and check that at some point, although I’m starting to think that might not be the issue as it’s slightly intermittent but perfectly timed
I was thinking that @stasha could be right: flakes flushed by the flow of the return line. You don't have to remove the tank, as you can unscrew the pickups. If the filters are NLA, this is how I fixed mine; https://www.ferrarichat.com/forum/threads/v-12-maintenance.307168/page-4#post-147684600 . In any case it's better to replace this filter but I would rather suspect your issue could be related to the cold start enrichment system or a bad hot control pressure (poorly adjusted WUR or damaged seals in the pressure regulator). So: just disconnect the cold start injector as this is the easiest to do, and see if it solves the issue. next step is to test the flow of the RETURN line. See k-jet maintenance guide for the details, from memory at least 1/2l should return to the tank within a 30 seconds time-frame (could be more on your car). if all the above do not exhibit problem, buy a k-jet test gauge and validate cold/hot control pressure as well as system pressure.
