1G idle adjustment

[90blktalon]

ok, I searched the vfaq and found the how to adjust the idle on a 1g. Before the adjustment my rpm was around 375-400, after the adjustment I got it to 650 and it sounded smooth. I adjusted the screw to try and get it to 750,but it stayed at 650.It sounded smooth so I cut the car off and ungrounded the wires and replaced the cap. I started the car back up and it stayed at 650 for a second then the idle started jumping up and down.Im going to do a boost leak test tomorrow, if there is any leaks would that cause this and why?

 

[hopwoodp]

Well, if you have a fuel leak, that will happen. If the boost leak test is fine, then I would check your compression. Check you spark plugs and ignition system if problems still persist.

 

[BUCK]

Base Idle & Base Timing affect each other - IMO due to the weird ass angle we have to view the Marks from when you are squatting down & peeking thru the belts & "see" 5 BTDC you are really set at about 7 BTDC - SO when you see 2.5 BTDC it's actually about 5 IMO - I try to be in the same position/angle whenever I set mine halfway between 5 & 0 BTDC & IMO that is 5 in the real world & "seeing" 0 would be 2.5 BTDC real world IMO... BTW on my Pocketlooger I'm pulling 22 - 25 advance at WOT (Tuning guide reccommends NO LESS than 15 at WOT) & see as much as 46 degrees advance on Pocketlogger in some throttle positions - ZERO knock on 92 or 93 Octane in Winter (which of course means I could bump up Timing OR Boost) - but it runs great & I don't want to fry this old Turbo quite yet - seeing 13 PSI on POS Stock gauge.

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1g Idle & Timing Adjustment STRAIGHT FROM DSM MANUAL...

- Reset ECU 15 Minutes to clear all the crap out.

- With car off
- Ground that pin on the Diagnostic Connector
- Fully warm car up, No accessories on.
- Run at 2500 rpm more than 5 seconds
- Let idle for 2 minutes
- Adjust BISS 700-750 rpm
- Cut car off
-Disconnect Jumper at Diag Conn

- With Car OFF
- Connect Timing Jumper
- Fully warm up car - No accessories
- Check CURB IDLE is at 750 + or - 100 rpm (may take a little while to settle down being you just reset BISS)
- Set Timing at 5BTDC (which means you'd see 4 IMO due to bad angle)
- Cut Car OFF
- Disconnect Timing Jumper
- Cut car ON
- Check Basic Engine Timing 8BTDC (kinda jumps from 7-9 usually).

- AFTER setting Base Timing correctly per the above you could then "bump up" Base Idle a little (50 - 100 rpm) to help with the Fan cut-on - The ECU can pull more than you can retard! - Some of us have BOTH Fans cutting on simultaneously so that is loading your Alt more than a stock setup - Typically you can retard one degree when setting Base Timing & it idles smoother as long as Idle is close to spec - Setting it where you see 4 will make it more resistant to losing RPM when fans cut on.

 

[eugenesxyby999]

where is the screw exactly to make the rpm stay constant?

im having the same problem and dont know how to fix it.

 

[hurdsy1883]

I have a 91 Eagle Talon and it idles at around 2500-2700 when I first start it. When it warms up it runs around 1100-1300 rpm, how do I fix this or is it where it needs to be?

 

[snowborder714]

I have a 91 Eagle Talon and it idles at around 2500-2700 when I first start it. When it warms up it runs around 1100-1300 rpm, how do I fix this or is it where it needs to be?

1G BISS Adjustment

 

[Callum Mccawe]

Base Idle & Base Timing affect each other - IMO due to the weird ass angle we have to view the Marks from when you are squatting down & peeking thru the belts & "see" 5 BTDC you are really set at about 7 BTDC - SO when you see 2.5 BTDC it's actually about 5 IMO - I try to be in the same position/angle whenever I set mine halfway between 5 & 0 BTDC & IMO that is 5 in the real world & "seeing" 0 would be 2.5 BTDC real world IMO... BTW on my Pocketlooger I'm pulling 22 - 25 advance at WOT (Tuning guide reccommends NO LESS than 15 at WOT) & see as much as 46 degrees advance on Pocketlogger in some throttle positions - ZERO knock on 92 or 93 Octane in Winter (which of course means I could bump up Timing OR Boost) - but it runs great & I don't want to fry this old Turbo quite yet - seeing 13 PSI on POS Stock gauge.

--------------------------------------------------------------------------------

1g Idle & Timing Adjustment STRAIGHT FROM DSM MANUAL...

- Reset ECU 15 Minutes to clear all the crap out.

- With car off
- Ground that pin on the Diagnostic Connector
- Fully warm car up, No accessories on.
- Run at 2500 rpm more than 5 seconds
- Let idle for 2 minutes
- Adjust BISS 700-750 rpm
- Cut car off
-Disconnect Jumper at Diag Conn

- With Car OFF
- Connect Timing Jumper
- Fully warm up car - No accessories
- Check CURB IDLE is at 750 + or - 100 rpm (may take a little while to settle down being you just reset BISS)
- Set Timing at 5BTDC (which means you'd see 4 IMO due to bad angle)
- Cut Car OFF
- Disconnect Timing Jumper
- Cut car ON
- Check Basic Engine Timing 8BTDC (kinda jumps from 7-9 usually).

- AFTER setting Base Timing correctly per the above you could then "bump up" Base Idle a little (50 - 100 rpm) to help with the Fan cut-on - The ECU can pull more than you can retard! - Some of us have BOTH Fans cutting on simultaneously so that is loading your Alt more than a stock setup - Typically you can retard one degree when setting Base Timing & it idles smoother as long as Idle is close to spec - Setting it where you see 4 will make it more resistant to losing RPM when fans cut on.

Just wondering why your saying to only ground the diagnostic connector for setting idle.....everywhere I’ve seen and searched says that you have to ground the timing connector as well.....

 

[steve]

There are two pins used for adjustments, the Timing Adjust connector and the Diagnostic Mode connector. When both are grounded the ECU locks the ISC position for setting the base idle speed.

With just the timing adjust grounded the base timing is locked to 5* BTDC so you can sync the signals from the CAS with the mechanical timing by rotating the CAS until your timing light reads the 5* BTDC.

The ECU also has a limit to the engine RPMs while adjusting the timing. If the RPMs exceed 1200 it drops out of the timing adjustment mode, IIRC.

 

[steve]

I suggest anyone who hasn't read the 1G Technical Reference Manual do so.
Most the the information applied to all the 1G's but some if specific to the 1990 cars. The section on the ECU is a must read for all DSM owners.

http://www.dsmtuners.com/threads/1g-dsm-1990-technical-information-factory-service-manual.517385/