Ok, so I am new here, or at least have never posted... I have used these forums to diagnose a few other issues based off other posters questions and the answers provided, however I am not finding what I need this time, so it must be time to ask for assistance lol... I have the RAVE downloaded as it seemed that "download the RAVE" is the most common answer in these forums lol, but it's rather confusing and I'm not sure it offers the trouble shooting I require.

I have a 96 disco, with coils not a distributor which is also confusing because I keep finding that the 96s had distributors assuming not all did tho as I don't. Anyway, if I jump in my Disco and start it up, she runs fine. Put it in gear, head down the road still fine. However, about 10-20 miles into a trip (sometimes much more or much less but on average 10-20) it will start to misfire as I can hear minor backfire via the airbox, shortly thereafter it feels as tho I am hauling a trailer full of bricks behind me, and if I attempt to maintain a speed it will keep backfiring, if I stay in the throttle it runs better, but constantly accelerating is not really an option, and it consumes a LOT of gas in the process... I had an issue with the crankshaft position sensor, or so I thought a while back, I replaced it, and when I did I noticed the wires were fried and cracked. I replaced the sensor (tho I think the wiring was the real culprit) and replaced the wires as far back as I could reach them, and when I did, I twisted them to one another to avoid cross interference, then slid them in "shrink wrap" and sealed them together. It ran beautifully for a couple months then started acting up again, but before the new wires it was a seriously different issue as soon as it went into gear (under a load) it would lose power and puke, and was only firing on half the cylinders most of the time. This seems similar but before I tear out the CkPS again and rebuild the wires, again, is this something anyone else has dealt with, am I neglecting to factor an easy fix into the equation? Any assistance, or insight would be grand. 96 Disco SE7 w/152k miles...

Thanks in advance,
ZeroRover

 

Check Engine Light on? If so, have you snagged the codes? What are they?

These are the basic questions anyone would ask and they help to drill down to the problem.

If no CEL then it becomes a little tougher. Just a thought but have you opened the shrink tubing to check the splices?

 

Yes the check engine light however is always on as the previous owner removed the downstream (i think) o2 sensors, the ones past the missing cats, when they redid the exhaust, however a red one that says service engine has since come on... I have a buddy bringing me a tester after work tonight, I will post codes, but I presume it will spit the generic "random misfire" code , and if you are not familiar with this year/model's CkPS location, checking those wires is a pain in the keester, have not had the time to do so yet, after code read out I will post results and move on to checking my wiring. I saw another post very similar to this in the forums and it was never given a clear answer as to what resolved it, was just hoping someone would read this and go "OH! That's a (insert sensor name here) problem!" lol

 

For now codes point the way. Might get easier or somebody might have had a similar issue if we keep this top of the heap. The downstream O2's main function is sniffing the cat's efficiency and yes, I know where the wires are.

 

Ok, well I finally got a chance to get it coded... And, I'm pretty sure my buddy is still laughing at my misfortune my 19! codes are as follows...

PO207, PO331, PO101, PO102, P1187, P1158, PO300, PO308, PO307, PO306, PO303, PO302, P1316, P1314, P1313, P1207, PO207, P1316

I haven't looked all these up yet, however I remember from past testing, pre-replacement of CkPS, that this looks like I am good on cylinders 1,4,and 5 and the rest are misfiring, along with the "general" misfire code lol fml

 

Man, tough to begin with so many. Two MIL's in particular catch my eye and are not like the others - P0207 is an injector fault; Injector 7 circuit malfunction and P1207 is another injector 7 fault; Injector 7 circuit open/short to ground. These are different than all the others so that has my attention. The rest are indicative of a huge overfueling problem. I wonder if Injector 7 is wide open? You can remove it's connector to see if the engine runs any different otherwise suspect 7 is broken and wide open flooding the engine. I've been there, done that before and the motor ran like crap, went through fuel quick. There are a couple of others regarding the Mass Airflow Sensor - P0102 MAF circuit - low input and P0101 MAF circuit range/performance problem. Check the wire connector. Try disconnecting it and reconnecting when engine is running, see if there's a difference. The others are 02 sensor - upstream heater circuit bank b and then the missing downsteams are throwing codes or the ECU is throwing the codes in place of them not existing. These are all GEMS related codes meaning they're not generics.

Look at injector 7 wiring and if you have to remove it and give it the rattle test - shake it to see if it rattles.

Check 02 sensor wiring on passenger side, uppermost.

Check the MAF visually - make sure it isn't black with soot and check it's connector to make sure it's seated firmly and look at pins for corrosion.

 

Ok, so yes my MAF is sooted, as I stated I have been having random misfires backfiring via the intake, is this safe to spray clean with a can of MAF cleaner spray? Also, I have a pair of injectors as I suspected a leaky one in the past, however the injector fault never came up last time I had issues and had it coded so I did not replace any, I will pull the wire to 7 and see if it stops "leaking" if not I will replace it... But, I won't get a difinative test drive on the injector issue until it stops misfiring lol

 

A leaking injector due to crud build up and a faulted injector due to electrical failure are two different issues. The first won't throw a specific injector code (although others will pop) whereas the ECU will throw a code on the second for sure. You have an injector with two electrical faults....... MAF cleaner is safe.

 

Alright, well, at first light I'm gonna head out and clean the MAF, pull my CkPS wiring back off and re-do it all again, applying a liberal amount of wire-coat to everything this time to rule out interference on that wire, the previous owner left the old downstream sensors in the center console when they removed them, and as they are the same model number as the upstream, swap them both and check the wiring, and as far as the injector goes, if i inspect the wiring and find no fault, do I then assume it is the circuit inside the injector and replace it? BTW, I had the fuel rail and injectors all out and cleaned once about 6 months ago, and getting to them sucked royally, so is there anything else I can try before replacing it to save that headache? Thanks for all the help and knowledge thus far

 

This is going by the ETM wire colors for your 96, they might be different colors than listed but for #7 it's yellow/red to fire, brown/orange to ECU common ground. I would check the injector's connector with a meter that the yellow/red wire isn't going to ECU ground (ECU case). Check the injector's coil isn't going to engine ground (shorted coil). That's about all you can do. The common ground (brown/orange) is the common between all injectors (spliced). Any injectors b/o wire should make continuity with each other. The MAF by the way is also tied into the brown/orange ECU common.......

I know it sucks, I don't sit behind a laptop. What doesn't suck is hearing your problem child fire up and run like never before eh.