420a lopey idle

[96talon_njj]

Hey guys, I have a 96 talon 420a motor. about 25k on motor. I threw a timing belt and got a used complete head from a junk and threw it on with a new head gasket. it has a lopey idle like it has cams in it but it doesn't. and a little bit of a knock sound but goes away when reved. any place i could begin?

 

[1slow97]

Sounds like you need to start out by double checking your timing.

 

[Cdc1221]

It sounds like a probable compression issue. Check your compression

 

[Fotowntalon]

Sounds like you need to start out by double checking your timing.

+1. My thoughts exactly

 

[96talon_njj]

my timing is spot on. i had my shop check it. Back last winter I threw a timing belt and bent 4 valves. so i got a complete head from a junkyard, had it shaved and slapped it on. loped ever since. i have not checked the compression. but what would cause it?

 

[4UH8ERS]

They all make a good point, considering you did not have the loping idle prior to the head replacement. If you shaved of an excessive amount of the head it may altered the timing by a 1/2 tooth.

Aside from the obvious that everyone else has mentioned. An EGR valve that is stuck open will create a very lopey idle that will of course dissapear under load or cruising.

 

[96talon_njj]

is there anyway of cleaning the egr valve?

 

[sestepney]

I'm having the same issue! I just finished a rebuild and the timing lined up as should. I installed an EGR block kit and I left the EGR solenoid connected but without the vacuum line connected. I didn't think this could cause a bad idle. I've been thinking maybe a vacuum leak.

 

[Josh97eclipse]

Egr will not cause a bad idle, the timing has to be off. Or a bad cam pr crank sensor.

 

[NeMiZiS]

I've had a lopey idle for 5 years.
Doesn't bother me or effect drive-ability or anything.

 

[TheRock0720]

I know you stated that the timing is dead on, but yes like what 4UH8ERS stated, if you shaved too much off, you could be off by a 1/2 a tooth which would throw the timing off. The solution here would be to get adjustable cams (anyone can chime in and correct me if I'm wrong). How much was shaven off the head? Anything shaven off the block?

In my case with this problem-
Mine was slightly off (forget by how much) but it caused the "loopy", and what seems to be a slight misfire, at idle. I ended up replacing the hydraulic tensioner and arm (as they both failed anyways) and voilà, problem solved and a nice and smooth idle!