Metric Mechanic 2900 Sport

[jneumss]

Perhaps the closed position on your throttle body needs to be adjusted? To idle, the engine needs the idle control valve to function, and a very small opening on the throttle body.

Ahhh, yes. I adjusted the TB according to the Bentley using a 0.0015 feeler gauge. However, I did see another method is to unplug the ICV and set the idle to 950 rpm by adjusting the small set screw on the TB.

I'll try this tonight.

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[ForcedFirebird]

Even a stock m20 has low vacuum compared to other cars (~11).

If the WOT switch in the TPS is malfunctioning, it will never go into the WOT maps, and it will continue to read the o2 (goes in open loop at WOT). But that doesn't explain the idle.

[325e '87]

Even a stock m20 has low vacuum compared to other cars (~11).

If the WOT switch in the TPS is malfunctioning, it will never go into the WOT maps, and it will continue to read the o2 (goes in open loop at WOT). But that doesn't explain the idle.

Quick off topic- I’m so glad you posted this comment. I hooked up a vacuum gauge to my engine a couple weeks ago while messing around with it and my gauge has a red/yellow/green zone, my stock i reads in the yellow and I poked and prodded for a WHILE looking for leaks. My engine idles very smooth, starts right up, runs as smooth as I expect so I ignored it in the end but damn if it didn’t bug me for a week or so....

[jneumss]

Quick off topic- I’m so glad you posted this comment. I hooked up a vacuum gauge to my engine a couple weeks ago while messing around with it and my gauge has a red/yellow/green zone, my stock i reads in the yellow and I poked and prodded for a WHILE looking for leaks. My engine idles very smooth, starts right up, runs as smooth as I expect so I ignored it in the end but damn if it didn’t bug me for a week or so....

I had exactly the same feeling. I just adjusted the idle and TPS and now it's idling well around 800 rpm.

I also passed emissions.

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[2mAn]

I also passed emissions.

sooooo now to the dyno? ;D

[redlightpete]

How did you adjust the idle?

[ForcedFirebird]

How did you adjust the idle?

The ECU adjusts idle, he adjusted the throttle switch. It has slotted screw mounts ans it should click at idle and click at WOT. Even if they "click", they should be tested for continuity since the breather hose tends to leak oil on them and they go bad. Two of the pins should be shorted at idle, two of them at WOT, and all 3 should be open in any other position.

[jneumss]

The ECU adjusts idle, he adjusted the throttle switch. It has slotted screw mounts ans it should click at idle and click at WOT. Even if they "click", they should be tested for continuity since the breather hose tends to leak oil on them and they go bad. Two of the pins should be shorted at idle, two of them at WOT, and all 3 should be open in any other position.

And it's worth noting that I messed with the throttle stop during engine break in to lock the idle at 2500rpm. I just never returned it to the stock position properly, so my TPS was not allowed to actuate the idle switch.

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[redlightpete]

Ahhh, yes. I adjusted the TB according to the Bentley using a 0.0015 feeler gauge. However, I did see another method is to unplug the ICV and set the idle to 950 rpm by adjusting the small set screw on the TB.

I'll try this tonight.

Sent from my Pixel 2 using Tapatalk

So, did you adjust the throttle plate to a 0.0015" gap, per the Bentley manual, or use some other method? Just curious because my 2.8 stroker with a sssquid chip also idles roughly at approximately 650 rpm. I've checked that the TPS has continuity at idle, and I set the throttle plate at 0.0015". Thanks

[jneumss]

So, did you adjust the throttle plate to a 0.0015" gap, per the Bentley manual, or use some other method? Just curious because my 2.8 stroker with a sssquid chip also idles roughly at approximately 650 rpm. I've checked that the TPS has continuity at idle, and I set the throttle plate at 0.0015". Thanks

Sorry I never replied to you. That is exactly what I did. Were you able to solve your issue with your low idle?

I am still struggling with a hesitation from off idle up to approximately 2800 rpm, but my idle is right around 700 to 750 rpm. My hope is to get the car running perfectly on the SSSquid chip and then piecing together a MS unit.

[redlightpete]

Sorry I never replied to you. That is exactly what I did. Were you able to solve your issue with your low idle?

I am still struggling with a hesitation from off idle up to approximately 2800 rpm, but my idle is right around 700 to 750 rpm. My hope is to get the car running perfectly on the SSSquid chip and then piecing together a MS unit.

Still have the low/rough idle issue. I need to check the fuel pressure and hook up a wide-band to verify what's up with the mixture. If both those check out, I'll try to follow up with SSSquid, as I'm not sure why the ECU wouldn't be forcing it to idle at 800 as the chip is supposed to be set.

So far I haven't found anyone that says they have a good idle running the Schrick 284/272 with the stock AFM. Judging by how much a tight valve adjustment affects the idle on a stock motor, it's not surprising that the AFM would be unhappy with the bigger cam.

I don't have any issues with hesitation at lower revs, though it does feel like it has a bit of a lean surge cruising at very small throttle openings (made more obvious by the loose old drivetrain).

[digger]

The solution is to just not use motronic and have full control over the icv, ignition timing and idle rpm. I recommend about 900-950rpm. This addresses the bulk of the issue but you'll still have the common plenum and Cross talking between cylinders which can be fixed with a set of itb lol

[ForcedFirebird]

The solution is to just not use motronic and have full control over the icv, ignition timing and idle rpm. I recommend about 900-950rpm. This addresses the bulk of the issue but you'll still have the common plenum and Cross talking between cylinders which can be fixed with a set of itb lol

Motronic shouldn't be dismissed totally. It's a step above jets on a carb and points on a diizzy. Quite programmable.

[digger]

Actually from a fuel point of view if you ignore emissions and economy which on a high performance engine is not always a big deal then a good carb is very hard to beat.

[nando]

it's too bad there's no easy way to use an EEPROM on Motronic (the WAR chip sortof is, but the software is crap).