1995 Jimmy Timing Questions

[Jessie00721]

Hello,

I have a 1995 Jimmy that has an obd1.5 system. Obd1 with an obd2 port. I am getting a p1345 code so my timing is not correct of what I assume. When checking the timing at around 800 rpm on an autoxray 7000 it shows it at -23 to -25 degrees. Is there a way to properly adjust the timing with the scan tool. I guess I am an off a tooth or 2 on the distributor. With a scan tool can I move and recheck the timing? What should it read? 0 degrees? Do I have to rev the engine beyond a certian rpm to check? Perhaps checking the timing the traditional way would be better? Does this distributor lock in place or can I advance it by turning it some. I keep reading that some lock into position and some can be moved. Have not actually looked at what I have, just trying to get a good idea till I go out and start messing with it. The truck runs ok, has a bit of a hard time starting and recently failed emission due to HC. Any instructions would be great!

Thank you for your time,
Jessie

[MT-2500]

Originally Posted by Jessie00721

Hello,

I have a 1995 Jimmy that has an obd1.5 system. Obd1 with an obd2 port. I am getting a p1345 code so my timing is not correct of what I assume. When checking the timing at around 800 rpm on an autoxray 7000 it shows it at -23 to -25 degrees. Is there a way to properly adjust the timing with the scan tool. I guess I am an off a tooth or 2 on the distributor. With a scan tool can I move and recheck the timing? What should it read? 0 degrees? Do I have to rev the engine beyond a certian rpm to check? Perhaps checking the timing the traditional way would be better? Does this distributor lock in place or can I advance it by turning it some. I keep reading that some lock into position and some can be moved. Have not actually looked at what I have, just trying to get a good idea till I go out and start messing with it. The truck runs ok, has a bit of a hard time starting and recently failed emission due to HC. Any instructions would be great!

Thank you for your time,
Jessie

Timing is not adjustable on it.
You can turn dist all day and not change timing.

Code 1345 is for camshaft reard setting out of specs/off.

To set camshaft retart you will need a engine capable scanner capable of reading cam shaft retard setting.
But First
Set dist with rotor to the no 6 on dist base with engine on TDC compression stroke.
Then start up and run engine and hook up scanner.
And read out camshaft retard.
Not timing advance reading.
The camshaft retard reading needs to be as close to - or + o degrees as you can get it.
Over 2-3 degress - or + can throw code.
Let us know how that goes.

[Jessie00721]

Spent a good part of the day messing with the distributor. Had to replace it due to bottom plate being cracked but no big deal, not much more for the entire assy. over what I already had spend for just the cap and button. Anyhow, did get it lined up much better, it was pretty hard trying to find out exactly tdc of #1 cyl. Seems to be on an angle. Eventually got it close and code has gone away. Did not try to adjust timing any. Starts right up and sounds good, scanner showed advace still around -24. Is that normal? Did not see a retard setting in the scanner but did not look very hard, was very pressed for time.

[blazee]

You should be able to access the EST wire (brown with black stripe if memory serves) behind the carpet on the passenger side. With the connector disconnected, you can check base timing.

[old_master]

No EST wire on 95 with OBD1.5, (actually there is but it doesn't get disconnected to check timing). The P1345 sets if/when cam retard is off approximately 27 degrees or more, (advanced or retarded). There are 13 teeth on the distributor gear which means, one tooth off, calculates to about 27 degrees. That's where the "magic number" for setting the DTC comes from. As MT said, camshaft retard desired spec is zero degrees, plus or minus 2 degrees, when engine RPM is above 2000. Cam retard is adjusted by rotating the distributor slightly. It actually does adjust base ignition timing, but in a round about kind of way: It perfectly aligns the Hall effect switch in the distributor, (camshaft position sensor) to the exact point when the camshaft is at TDC compression for #1 cylinder. The cam sensor and crank sensor are used for ignition timing, cylinder misfire detection and cylinder identification. When both sensors are properly adjusted/calibrated, the ECM can accurately adjust/control ignition timing. The crankshaft position sensor is calibrated by performing a crankshaft position sensor relearn. Adjusting cam retard to zero degrees also perfectly aligns the rotor segment so it is lined up with each terminal in the cap when the ignition coil fires. This keeps the air gap and crossfire inside the cap to a minimum.

You might want to check fuel pressure and leakdown, that might be the cause of your high HC.

[Jessie00721]

Your explinations clear some stuff. I will say I am on the right tooth now. Wanted to get the timing perfect even though it seems to run ok now. I am a little confused about setting base timing. I read to disconnect a wire at the distributor is some places, disconnect a wire at the passenger compartment on others, dont disconnect a wire. I have no idea what is right. Another concern is I see a mark on the harmonic balancer but I dont have the little saw tooth looking thing that would say 0 degrees and so forth. Did not know if checking it with the scanner is possible but that seems to be reading the advance. Does disconnecting the wire stop the computer from automatically advancing? Sorry, just not sure on what is right and how that works exactly.

Thanks,
Jessie

[MT-2500]

Originally Posted by jessie00721

your explinations clear some stuff. I will say i am on the right tooth now. Wanted to get the timing perfect even though it seems to run ok now. I am a little confused about setting base timing. I read to disconnect a wire at the distributor is some places, disconnect a wire at the passenger compartment on others, dont disconnect a wire. I have no idea what is right. Another concern is i see a mark on the harmonic balancer but i dont have the little saw tooth looking thing that would say 0 degrees and so forth. Did not know if checking it with the scanner is possible but that seems to be reading the advance. Does disconnecting the wire stop the computer from automatically advancing? Sorry, just not sure on what is right and how that works exactly.

Thanks,
jessie

the timing is not adjustable.
It can not be set.

[old_master]

1992 through mid 1995 4.3L "W" engines have OBDI and the EST wire must be disconnected to adjust base timing correctly. When the EST wire is disconnected, the ECM can not control ignition timing.

Your late 1995 has OBD1.5 and the EST wire is always connected to the ignition module. As far as setting base timing on your engine, it is done by adjusting camshaft retard. Ignition timing is constantly controlled by the ECM so camshaft retard must be adjusted to spec for ignition timing to be correct. The "saw tooth" timing index is not used on your engine. You don't need a timing light, (it wouldn't tell you anything anyway). You read ignition timing on the scan tool. This image shows the timing mark locations for aligning #1 cylinder to TDC:

[Jessie00721]

Originally Posted by old_master

1992 through mid 1995 4.3L "W" engines have OBDI and the EST wire must be disconnected to adjust base timing correctly. When the EST wire is disconnected, the ECM can not control ignition timing.

Your late 1995 has OBD1.5 and the EST wire is always connected to the ignition module. As far as setting base timing on your engine, it is done by adjusting camshaft retard. Ignition timing is constantly controlled by the ECM so camshaft retard must be adjusted to spec for ignition timing to be correct. The "saw tooth" timing index is not used on your engine. You don't need a timing light, (it wouldn't tell you anything anyway). You read ignition timing on the scan tool. This image shows the timing mark locations for aligning #1 cylinder to TDC:

Ok, thanks again. I guess I am done messing with the timing. I did not look for a cam retard section in the scan tool but it must be 0 to +or- 2 according to your earlier calculations cause the p1345 has went away. Thanks for the explinations!

[old_master]

Originally Posted by Jessie00721

.....I did not look for a cam retard section in the scan tool but it must be 0 to +or- 2 according to your earlier calculations cause the p1345 has went away...

The P1345 sets when cam retard if off by MORE than 27 degrees. If P1345 does not set, basically it's telling you you're "in the ballpark" and the cam retard adjustment is a "fine tune" to get it to zero degrees. Theoretically your timing could be off as much as 26 degrees with no check engine light. Without checking cam retard, you'd never know it. The ECM only has a certain range that it can adjust timing: if cam retard is off 26 degrees, that's 26 degrees of ignition timing that the ECM can't compensate for! As a result, you lose performance and fuel mileage!

[Jessie00721]

I talked to tech support tonight about the autoxray 7000 and it does do the cam retard, I was just in the wrong section. So I am hoping to hook up the scanner tomorrow and see if it works like they told me, if so I will adjust the cam retard and let you know how it goes. Thanks again.

[MT-2500]

Originally Posted by Jessie00721

I talked to tech support tonight about the autoxray 7000 and it does do the cam retard, I was just in the wrong section. So I am hoping to hook up the scanner tomorrow and see if it works like they told me, if so I will adjust the cam retard and let you know how it goes. Thanks again.

You are welcome.

Yes it needs checked.
Needs to be as close to -0 or +0 degrees as you can get it.
When checking/setting it after moving dist the RPM needs to be bumped over 1K for the new setting to read out on scanner.

Another problem on setting it is some dist are fixed/do not have any turning adjustment.
And if a replacemnt dist like yours sometimes the dist gear has to be reset 190 degrees.
Post back you readings.
If it is off over 1 degree - or + and you can not turn dist to bring it back into specs/ post back for more help

[Jessie00721]

Looks like I gotta wait till monday to talk to autoxray again. Did what they suggested but cam retard still not there. Need to get info whether it will work or not.

[old_master]

I just downloaded and went through the user guide for the Autoxray 7000. It appears to be an EOBD scan tool, the "E" means "Enhanced". In other words, it can access a few more areas in the ECM, and do a few more things than a code reader can. It says it has "True bi-directional capabilities", key word being "capabilities". I have no idea how they get away with making that claim. This tool doesn't even come close to being fully bi-directional. There are functional tests that can be done with a capable scan tool, that will allow you to operate darn near every electrical device on the vehicle, right from the scan tool. Typically you need to get into at least the $2K range for a scan tool that will do functional tests. Nowhere in the guide does it even think about mentioning camshaft retard data. It does have some nice features though, like graphing and code look-up. I suppose it's possible that there's a menu that will access camshaft retard and maybe even crankshaft position sensor relearn. Let us know what they say, I'm curious.

[MT-2500]

Originally Posted by Jessie00721

Looks like I gotta wait till monday to talk to autoxray again. Did what they suggested but cam retard still not there. Need to get info whether it will work or not.

If you have the instructions with it read them about 3 times.
Also run a web search on autoXray.
I remember on some scanners the cmshaft retard readings are with miss fire data.
Go threw everything and you should find it someplace.
Good luck