Hey!
I have a 1996 magna v6 which has started to miss when in D idling at the lights at intersections, badly when going up hills at low revs and is worse still with loads on engine i.e a/c turned on. I am a mechanic myself But am struggling to source a test procedure for the tps!!!!! I no the airflow meter is fine and i dont think it would be the 02 sensor because it is quite a splutter and will happen in quite random succession! I have cheched all plugs all are clean and leads are all fine dizzy cap fine! I have a suspicion that it could be the coil breaking down becasue it seems to get worse as the engine gets hot. Would anyone be able to give me any advice and give me a test procedure for the coil and tps?????

Much appreciated!:woot:

3.5l V6 TR TS . . . . . . . no such thing, buddy.

its a 1996 magna v6

Check that your plugs are not covered in oil, as the o-rings start leaking oil from the rocker cover gasket with time

plugs and leads are fine i have checked those

I had something similar with a KS, many years ago.

Did the leads and plugs, still no good. Idled sort of OK, up hills and under load was awful.

2 ideas, easy one to check is the O2 sensor. A quick and dirt check is to find the plug and check for resistance on the 2 leads with tracers. On my TJ was open circuit. However this really manifests itself as a massive flat spot when accelerating, the engine is nice and smooth otherwise.

On the KS eventually found that the injectors had had a tank of crap fuel from a company fuel tank.
Took car to injector place. Had all the injectors ultrasonically cleaned. They showed me the before results, several were flowing at under 50%, after a good clean there was no practical difference.
Car ran beautifully afterwards.

Another suspicion is that the coil unit is breaking down in the distributor. This has been mentioned before on these forums.

Gerry

OP: we need to know if you are talking 3.0L TS or 3.0L third gen - totally different engines. Got an engine number?

On the second gen TS the ignition coil is bolted to the back of the intake manifold, in the third gen it's inside the distributor. BUT it does sound like the ignition system is struggling.

Hey mate
Its a 3.0l ts, the coil is bolted to the back of the intake manifold! How can i test this???? have never worked on mitsis really

O.K!
Sooooo....... Cars need 3 things to run. Spark, Compression and fuel. If one of these systems isnt working or is faulting Your engine is going to run like shit or not run at all! generally if your car is missing you would start by checking the compression, they should all be within 20 percent difference max between eachother, if you find a cylinder with low compression squirt some oil down the cylinder and test it again .. i compression tests ok the rings are at fault, if it still tests bad it is either going to be laking out the valves , the head gasket is blown or the head is cracked, in either of the last 2 cases the head will still have to come off! If all this checks out fine then you will need to check the spark . start by checking the plugs , check the gap between the electrodes check for fouling also check the electrode isnt rounded. Next check the leads check the resistances of all the leads including the one to the coil. if the resistances are excessively high replace the leads also if the insulation is worn or there is tracking in the plugs on the ends... this looks like white powder marks and is caused by the spark arcing onto something else.next check the distributor cap and rotor and rotor button , once again check for tracking in the cap, water and corrosion or oil. check all the contacts and rotor arent burnt or worn also with the rotor button. If your car still has points check them for arcing or burning and perform a voltage drop test across the points. also check any wiring to the distributor and make sure the shaft isnt bent. If all that checks out you need to check the coil you will need to look up a test procedure especially with modern vehicles. also check the coil for arcing marks (tracking). Quite often coils will cause a miss when engines get hot because the coil heats up and the resistance increase and the coil starts to break down...... If this all checks out the problem could also be with the fueling . electronic fuel injection systems use an ECU to receive information and adjust the amount of time the injectors pulse for (how long they are held open for) and also ignition timing in newer engines. The ECU gathers reading from the Airflow meter, The Oxygen sensor, The throttle position sensor and the temperature sensor for fueling all of these can contribute to a miss if the are faulting . generally these can be quite complicated to test so you will have to look up a test procedure for your specific vehicle. Finally your fuel could have blocked an injector or the injector might not be pulsing or your fuel filter could be blocked! That should keep you busy if your car has a missing fault!