After lots of BS,, I finally have my bird running again. As the topic says,, I'm having problems getting the car to idle correctly. Its a rebuilt 305 with faily high compression (around 10.5), factory TPI cam with 1.6 rockers, all msd ignition and a BBk 52mm throttle body (factory one was cashed). The TPS is set at about .58v closed and is a new sensor. I'm pretty certain the idle air valve is still good,, min. air idle is 400rpm.
The problem is the idle is 'alright' sitting still and fine at high idle when 1st started but,, if the car is moving and you put the clutch in it want's to almost die (drops to about 500rpm) then jumps to around 1000rpm and starts trying to die ever few seconds. The fuel pressure is good (about 47psi) and the pump is new along with the filter. The injectors have been cleaned and flow matched. The timing is set at 8º with the wire disconnected from the distributor.

Would not having the vaccuum lines hooked up to the EVAP can have a part in this problem ? I have that and the cruise vac. ports blocked off until I can get a vac. hose diagram for them or wold this be a problem from a bad sensor or the ECM(prom) not agreeing with with the higher lift, FP, and throttle body. It's a MAF TPI engine so I didn't think that the rather minor mods would effect it to much or am I wrong about that ?

It runs great with the exception of a terriable idle. Most everything on the engine (sensors/ignition) is new. Any help and/or ideas are much appreciated

(* thanks to vader & fjk (?) for the help last time,,that mustang sold quick )

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DB,

Other than the higher-than-stock fuel pressure, everything should be fairly normal. I've got 1.6:1s on my stock-cammed TPI with no adverse effects, so I'd assume that isn't a problem. My base timing is at 10-11° BTDC, so I'd guess that's O.K. for you, too.

As long as you have capped or plugged the EVAP and cruise vacuum fittings, that shouldn't present a problem. The extra static compression is not a major concern, since the cam doesn't allow for a great deal of overlap and therefore the manifold vacuum should be reasonable at idle.

I'd guess it is a result of a sluggish IAC stepper motor and/or IAC air passages that are dirty or restricted. You can remove the IAC, carefully remove the pintle, clean the motor and worm gear, place one drop of oil on the gear, then reassemble. Work the pintle back into the rack gears, then thoroughly clean the IAC air passages. I understand that the TB is not original, but it doesn't take long to build up deposits in the passages.

Just a guess.

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Later,
Vader
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"Make Me Bad"
Adobe Acrobat Reader 4.0

 

Hey Vader
thanks for the guess,, I'll have to go out and try putting a bitof oil on the IAC,, I never thought of doing that. As far as cleaning tho,, I have cleaned the entire plenum as well as port matched it. Also there is only about 3 miles on the engine so far,, and about 20 mins of running so I'm faily certain it's not to dirty just yet.

I've watched the timing after resting the code from unplugging the dist. and it doesn't seem to be doing anything out of the ordinary when it misses/dies,,it's kind of more like the car turns off for a split second a few times then rev's itself (not much over 1k rpm)to retry getting a good idle speed again. The timing light never misses a flash tho when it does this.
I didn't think the mild mods would affect the ECM too badly since the MAF is 'supposed' to be a little more tolerant of changes.
Guess I'll go see if oil helps. Thanks Vader

 

O-kaaay,,, I don't think I'll have to be putting oil on there after all,, there is oil seeping out from my throttle blades,,, WTF ?? It hasn't been smoking/smelling like it's burning oil. I'm guessing this is comming from that tube that runs to the valve cover?(they aren't factory) But they have a baffled grommet/plug
I'd also assume this is a big problem to the idle thing mentioned above,,, should this be sucking that hard to be pulling oil from the motor ?? (I'm really starting to hate cars )

 

VADER, interesting point about disassembling the IAC and cleaning it.

How exactly do you remove the pintle? Will gently pulling on it as I rock it from side to side cause it to come all the way out?

I'd like to take mine apart to clean it.

Thanks,

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

[This message has been edited by JakeJr (edited November 19, 2000).]

 

If you've only had it running about 20 minutes, then you're gonna get all kinds of weird stuff going on. Idle won't be right until after a decent drive. As for the oil, the rings may not be seated very well yet causing it from blowby. Run it for a while, and monitor it to make sure things don't get any worse. If things do get worse, give us some more details, and we'll see what we can do for you!

Good luck!

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Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Awaiting results from all 8 ASE tests.

Starting to look like the Kicker poster child!

 

[QUOTE]Originally posted by deadbird:
"there is oil seeping out from my throttle blades,,, WTF ?? It hasn't been smoking/smelling like it's burning oil. I'm guessing this is comming from that tube that runs to the valve cover?(they aren't factory) But they have a baffled grommet/plug
I'd also assume this is a big problem to the idle thing mentioned above,,, should this be sucking that hard to be pulling oil from the motor ?? "

This to me sounds like a bad PCV valve. That hose that is connected to the throttle body and the valve cover of for the suction from the crankcase. It is not supposed to blow out. The vapors are vented out through the PCV on the other side and into the plenum.
If the PCV is not working right then the vapors along with some oil will be sucked up to the throttle body instead of through the PCV.
I have read that a bad PCV will cause poor idle but don't know how much.

 

Maybe I'm an idiot and got the wrong one (no comments please ),, but I did get a new PCV valve knowing the old one was shot,, but I never had that problem B 4. I may go drive it some more here in a bit since the dark makes the a little easier not to spot me since the car doesn't really have any exhaust past the 'converter'
Might the oil problem be from the **** poor design of the grommet/wanna be baffle as well ? It really is a bad design especially compared to the factory valve covers, which I may just go get a new pair of and ditch these crap ones.
I appreciate all the help & ideas guys,, thank you.

 

Vadar,
I would also like additional info on the IAC disassembly and cleaning. Thanks
DS

 

Has anyone had one of these IACs apart? Is the pintle shaft a worm gear that can be turned out and lubricated?
If anyone tries this, for reassembly I notice the service manual says the measurement from the collar of the IAC to the pintle tip should be 1 1/8 inch.

 

Hey guys,
I got in touch with the guy who did my motor last night and asked him about the situation. I think it was JP that called it correct about the rings,,, I do have 15 miles on it but they don't amount to crap as he told me, He said to just get it out and drive it at a steady rmp of around 2200 for awhile to get everything seated properly.

As far as the idle problem itself he said with running the high compression I need to Decrease my timing back to the factory 4° and just wait until the ECM has 'learned' it's info to run better. As soon as I can get some exhaust rigged up I'll have to take it for a real drive.

Thank you for all the help guys