94 jimmy timing problem.

[djwmarquez]

Hello everyone

I am new here but i am hoping you can help me out. I have a 1994 Jimmy that i am having a problem with. I have a rough idle which i have just thought was due to having 164k miles on it, but it is becoming harder to start. I have replaced the cap, rotor, ignition module and the coil recently. ( Basic Maintenance ). The vacuum hoses are all in good condition. While i was doing the work i noticed that when i took a timing lite to the harmonic balancer that the timing mark was fluctuating. It was not even really near the timing marks. The truck runs ok, idles rough, and accelerates ok throughout the driving range. The timing smoothed a little bit when i replaced the coil. I was thinking i might have a MAP sensor problem.HELPPPPPPPPPPPP.
I was hoping that since i don't have the emissions label someone might be able to help me find the timing degrees and any other helpfull advice to get this timing problem under controll. Thanks in advance for any help.

[herkyhawki]

You must unplug the brown wire under the dashunder carpet on passenger side before you check the timing.

[djwmarquez]

Thanks for the response,
i appreciate it.
The next time i check the timing i will try that. The question i have thought is, why is the mark on the dampner not even showing up near the timing marks. It seems like it is showing up as retarded beyond measure. I am begining to think that maybe my knock sensors are not working, or atleast one of them. . Since they controll timing i am thinking that maybe they are sending false signals to the ecm causing it to retard the timing.
The Jimmy is very hard to start in the morning and when it has been sitting for a while. It has to be cranked several times and the gas pushed all the way to the floor before it will start. Sometimes it will start on the second crank or so. I appreciate any help and all the suggestions guys. thanks again

[rlith]

Until you pull that wire, you won't get an accurate reading on the dampner/gauge. The brown wire disconnect the ECM from the distributor. The reason for this is that when connected the ECM controls the timing based on a lot of things, but more pointedly it uses the knock sensors. When the knock sensors detect, they send signals to the ecm which then retards or advances as need (sometimes several times a second) So as stated above, disconnect the wire or you won't get an accurate reading with your timing light.

[billm557]

djwmarquez,
Have you solved your starting problem? I have a 96 Jimmy that has the same problem. I have to crank it over around three times before the engine will fire.
I haven't checked the timing as of yet.

Any thoughts???????????

[herkyhawki]

Originally Posted by billm557

djwmarquez,
Have you solved your starting problem? I have a 96 Jimmy ...
I haven't checked the timing as of yet. ??

BillM, There is no ingition timing adjustment on 1996.

[billm557]

So from what I've been reading, the issue with it not starting points to the full pump????