Big Cam Idle Issues?

[mtocrs1]

Long story short. Purchased a GN that was built in the late 90 from a lady that got it from her brother. (Now departed) The engine appears to be an aggressive build.

The throttle blade was adjusted to raise idle past the point of IAC control. I corrected, reset TPS, IAC etc.

Now that the idle is controlled by the chip, it runs rough and loads up, smells of fuel etc.
Touch the throttle and it comes to life smooth as can be.

I figured it was the old ATR chip. Swapped it out for the SD2 setup.

Same thing idle is rough smells of fuel but smooths out instantly with throttle.
No matter how much I play with the SD2 fuel tables the O2 reads like 70mv indicating lean....but again smells of fuel like its rich.

I have checked for exhaust leaks and vacuum leaks. Replaced the O2 and the usual stuff.

I am thinking it's either a big cam issue and I need the chip idle set higher or a faulty injector.

Wideband not installed yet....
Idle speed programmed to 875


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[20psiofevil]

Sounds like a timing issue to me. I would go about the steps to verify timing using the sticky and post back with results.

 

[Wahoo]

What size can is it? Post a vid?

 

[mtocrs1]

What size can is it? Post a vid?

No idea.


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[mtocrs1]

Sounds like a timing issue to me. I would go about the steps to verify timing using the sticky and post back with results.

I didn't think of that, I'll try and find the sticky


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[No disintegrations]

Put a vacuum gauge on it and see how much she pulls. Big huge cam will not pull much vacuum. A more normal street cam should pull ok vac.

 

[mtocrs1]

Put a vacuum gauge on it and see how much she pulls. Big huge cam will not pull much vacuum. A more normal street cam should pull ok vac.

Wouldn't the map reading provide the same info?


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[mtocrs1]

Another thing I need to mention is that the car won't stay running when cold without playing with the throttle.
Also I have checked compression and they were all 145 cold.


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[No disintegrations]

Wouldn't the map reading provide the same info?


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sure so what is it?

 

[mtocrs1]

sure so what is it?

I'll have to check once I get back home.


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[TurboBuRick]

SD2 chip can be tricky without a wide band. Specially cold start. Really sounds like LACK OF fuel. I know you said it smells rich but o2 reading 070mv also suggests lean. Have you had a look the spark plugs? That might give a indication if it's a bad injector/s.


Rick

 

[mtocrs1]

SD2 chip can be tricky without a wide band. Specially cold start. Really sounds like LACK OF fuel. I know you said it smells rich but o2 reading 070mv also suggests lean. Have you had a look the spark plugs? That might give a indication if it's a bad injector/s.


Rick

Yeah I'm going to try and get the Wideband in. Only hold up is the downpipe doesn't have a bung and I don't trust my welding skills on the Downpipe.
When the O2 was reading lean I added a ton off fuel and the O2 reading didn't change.
I pulled just one plug. It was somewhat brown but was a bit wet.


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[whitehot1]

Do you have a scanmaster? if so can you post all the readings off of it at idle?

 

[TurboBuRick]

Yeah I'm going to try and get the Wideband in. Only hold up is the downpipe doesn't have a bung and I don't trust my welding skills on the Downpipe.
When the O2 was reading lean I added a ton off fuel and the O2 reading didn't change.
I pulled just one plug. It was somewhat brown but was a bit wet.


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Rich misfire will read lean as well.

I would read all the plugs to verify a global or local condition.

 

[bison]

Clean/flow injectors or replace. Verify base fuel pressure. Make sure chip is burned for injectors. If it still does it try introducing a vacuum leak and see if it clears up


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[mtocrs1]

sure so what is it?

map is 36.8 at idle, im not really sure how interpret that. Boost is -18ish

 

[TurboBuRick]

map is 36.8 at idle, im not really sure how interpret that. Boost is -18ish

Idle map seems low. What is map reading key on engine off?

Also save the file before you turn the key off so the parameters are saved.

 

[BEATAV8]

Your MAP sensor is configured for "2 Bar sensor" on the analog input settings. Is that correct or does the car have a 3 bar installed?

Key On / Engine Off, your MAP should read very close to 100Kpa (assuminig you are reasonably close to sea level). If not, change the input setting and exit / reopen powerlogger console and re-connect to powerlogger.

Also its absolutely critical to re-wire the MAP power to the TPS sensor +/- 5V power as described in the checklist on pg 4 of the instructions.

 

[20psiofevil]

I have a fairly large cam in my engine and have went through this. Had several issues though. All the while was pulling -16hg/vac at idle. One issue was with accel ceramic boot plug wires would not seat correctly onto the plug and was arching off the block. Another issue was tune and the timing was not correct. 26-28* advance headers would glow cherry. Advancing it to 32* was what it took to really clean the idle up.

 

[larry33kc]

Watching. I'm having a similar situation