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1986 Ranger XLT 2.9L V6 Cold/Warm Bad idle and cuts out sometimes while idling or on movement


Dexagama

New Member
Joined
Feb 17, 2020
Messages
3
City
El paso tx
Vehicle Year
1986
Transmission
Manual
Even if its cold or warm it doesn't die it just runs very rough while idling or driving sometimes it cuts out for like half a sec on 1500/above rpms, very chuggish

Firing order was 1,4,2,6,3,5 when it's supposed to be 1,4,2,5,3,6 so 5 and 6 we're connected backwards and it backfired a lot, then i fixed that and runs like 5 and 6 weren't even connected, while idling i disconnected the spark wire for number 6 and 5 and made no difference at all (all cylinders have spark)

it has grey smoke comming out of the exhaust (maybe its burning carbon deposits form sitting like 2 years when it started to work badly at first with kinda black-ish smoke)

the oil smells like gas (but it was because of the FPR which i replaced already, it made a slight difference)

the engine shakes a lot

it has no vaccum leak

replaced the FPR, Map sensor, TPS, Spark wires, Distributor cap and rotor, Both Fuel pumps and relays, the IAC seems to be good, Replaced the computer and o2 sensor too
 
Last edited:
Welcome to the forum

You don't mention spark plugs but I assume they got replaced as well, what did the old ones look like, especially 5 and 6?

You will probably need to do a compression test before spending any more money on it
1986 2.9l uses Batch Fire injection so a bad injector won't cause a steady misfire like you have with 5 and 6
And you have updated spark system so shouldn't be a spark issue at this point

Remove all spark plug first, then do compression test on all 6 cylinders, write down results
Expected compression is 160psi with 9.0:1 ratio

The rough running and grey smoke is unburned fuel from the misfires
 
Welcome to the forum

You don't mention spark plugs but I assume they got replaced as well, what did the old ones look like, especially 5 and 6?

You will probably need to do a compression test before spending any more money on it
1986 2.9l uses Batch Fire injection so a bad injector won't cause a steady misfire like you have with 5 and 6
And you have updated spark system so shouldn't be a spark issue at this point

Remove all spark plug first, then do compression test on all 6 cylinders, write down results
Expected compression is 160psi with 9.0:1 ratio

The rough running and grey smoke is unburned fuel from the misfires

The plugs on 5 and 6 were full of carbon before i changed them and the new ones are full of carbon too so its burning something, cleaned them and got them back in

The compression test was good some cylinders may vary 2-4 psi higher or lower but mostly 157 psi

i changed the map sensor (turns out somebody got the old one in and not the new one) and it made a difference it doesn’t missfire as much as it was doing but still does, mostly on movement

im maybe thinking about a distributor timing issue
 
Last edited:
Sounds like in the 2nd video that you have a pretty bad vacuum leak somewhere. Get that fixed then go from there. A vacuum leak will cause some idle issues and stalling too.

If you have carbon caked spark plugs you are most likely burning oil from worn piston rings or valve seats, just went through this with my 88 Bronco 2 and I ended up doing an engine replacement (not cheap).
 

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