hi all i have a problem i hope you can help? vr v6 auto is missing at idle and above! i have checked or replaced the following spark plugs ignition leads coil packs and dfi module fuel filter throttle body removed and cleaned IAC Valve removed and cleaned computer codes checked no codes found compressions checked all above 150 psi air filter injector cleaner in tank thats all i can think of that i have done! but to no avail any ideas will be greatly appreciated!
Miss is almost always a cylinder failing to fire. If you only checked the spark plug leads, replace them. Unless they are new already replace the spark plugs too. Feel how tight the leads are on the plugs. They should be tight.
plugs are new! leads were checked for resistence and physical damage all ok sprayed aero start all around the manifold gasket area with engine running and it made no differance?
It may not be an electrical miss bazza, check fuel pressure.. if you have a blocked reg/rail pressure (from dirty fuel) will be excessive as it restrics against the pump making it work harder. definately causing a miss. also could be a leaking injector, a dirty terminal at injector or in some cases a vaccuum leak, checked Map sensor purge hoses and the ones at the throttle body? or worse case senario you could have valve recession.. $$$$$$$
I would put my money on a new set of leads fixing the problem. Checking the resistance will only tell you if the lead is really shagged. Resistance measurement will not pick up a lead that causes an intermittent miss.
would not a leaking injector be visible fuel leak at the site of the injector? MAP Sensor is attached to firewall and has 1 vacuum hose to it and a wiring connector?
If you have doubts about the injectors have them cleaned by an injector specialist. The injector specialist will do a leak test and flow test on the injector before the clean it. That will cost you up to $250 though for a full 6. You can check that the injector is firing using a test light or multimeter on the plug of the injector. If you want to fix your problem go and get a new set of leads for $50 - at least rule them out. They are the most likely. I have seen it time and time again on here. Guys just seem unwilling to change the leads but will go and change the coils and dfi module etc etc. Theyre not hard, theyre not expensive.
kopper is right.... my leads showed up the correct resistance when measured and was still missing...... it turned out to be ingnition lead number 1 for the second time.... this lead is common to stuff up as when it leaves the coil pack its route has a huge bend, i guess putting a lot of stress on this lead compared to the others.
well i have just installed a new set of bosch leads and it has made no difference at all? crank angle sensor and balancer have also been replaced in the last few weeks! any other ideas?
You could have a blocked/slightly clogged injector, have you run a bottle of Nulon Injector Cleaner in your tank with $20 worth of 98 RON Premiun fuel and 1lt bottle of Metho, pour that in your empty tank and take her for a run, when did you last change the fuel filter too?Dont be affraid of the metho, all it does is mix with any water in your tank and spit it out the injectors getting rid of it. Try that champ.
Is the miss always there or just most of the time? I have noticed i have a miss throws my idle out but only sometimes. I have new leads new fuel pump and cas, might have to try new plugs, otherwise ill get pressure tested again.
OK, new leads - now we can move on. Have you got a mutimeter or test light? Put the probes on the two terminals of the injector. If its a multimeter set it to the DC volts scale. Run the car and check each injector. The test light/multimeter reading should pulse the light/a reading for each injection. Next use your multimeter to measure the resistance of the injector while the car is off. Resistance should be around 14 ohms I think, with a fairly tight tolerence. Measure each and if one is out it should be obvious. Dont take too much time to do this though as an injector with a low resistance can damage the ECU. This test will tell you injector is totally stuffed. To check for a leak the best bet is to, as above, take it to an injector specialist unless you have access to working spare parts and a bit of time.
INJECTOR blockage or LEAKAGE. If its leaking it wont be visable, it leaks into the chamber, overfueling and may cause early ignition/ a miss. To test leakage you can take the injecots out with the rail still attached, then put newspaper under the injectos and then turn the key to just before starting position, the injecors should squirt, leave the key in that position and watch if any of them keep dribling fuel after the first primary squirt, if so, leaking. Cant really test blockage, unless you see one of the injectors didnt spray any fuel, which means you wold be running 5 cyl. Try the injector cleaner with metho and Premium fuel to clean the injectors.
Yeah, do that and take it for a straping, after youve run that out the system, see if it makes a difference. If no change, take the injectors out of the intake manifold and do as I said before to test for leakage.
