Questions about IAB and EGR

Saleen308 · 03-18-2001, 09:55 PM

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I am in the process of trying to find out why my car idles so high. I am slowly trying to eliminate potential problems.

Does the vacuum hose on the back of the EGR have a certain amount of vacuum at idle? I hooked my gauge up to it and it wouldn't register any thing. I put my finger over the end of the hose and I could just barely feel any vacuum .

I checked my IAB(I guess that is what that thing is called that mounts on the side of the TB). It was clean. I blew air into one side of it and could feel air coming out the other side. Is this normal?

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347 stroker, TFS track heat heads ported and polished, ported GT-40 intake,70mm TB ans spacer,75mm MAF,K&N,24lb injectors,1 5/8" mac long tubes, off road h-pipe, FMS "z" cam, FMS plug wires, NGK plugs, FMS aluminum drive shaft, Omega 1.6 RR, FMS 3 core radiator, Flowkooler waterpump, World class T5, Pro 5.0 shifter, Autometer Fuel psi gauge, Autometer A/F gauge, caster camber plates, Koni reds, Pan hard bar, S.S. brake lines, Centerforce Dual Friction clutch, Walbro 255lph FP, Lakewood drivesha

vkaro45 · 03-18-2001, 10:28 PM

The EGR doesn't have vacuum at idle so that seems to be ok. I'm not sure what you mean on the second part but there is a passage through the IAB with a valve in it.

Make sure timing is correct, adjust idle with the IAB disconnected, set the TPS. If this doesn't work you could have a vacuum leak. Have you checked for codes?

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'89 GT work in progress
'66 289 coupe even more work

Saleen308 · 03-18-2001, 10:48 PM

The check engine light is not on. Doesn't it have to be on to create a code to try and retrieve?

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347 stroker, TFS track heat heads ported and polished, ported GT-40 intake,70mm TB ans spacer,75mm MAF,K&N,24lb injectors,1 5/8" mac long tubes, off road h-pipe, FMS "z" cam, FMS plug wires, NGK plugs, FMS aluminum drive shaft, Omega 1.6 RR, FMS 3 core radiator, Flowkooler waterpump, World class T5, Pro 5.0 shifter, Autometer Fuel psi gauge, Autometer A/F gauge, caster camber plates, Koni reds, Pan hard bar, S.S. brake lines, Centerforce Dual Friction clutch, Walbro 255lph FP, Lakewood drivesha

vkaro45 · 03-18-2001, 11:22 PM

No, my Lincoln T/C (same setup) had a bad egr valve. Pulled a code 34 but no check engine light. The diaphram was leaking causing a vacuum leak.

Capri306 · 03-19-2001, 09:30 AM

If you were able to blow air into one side of the IAB and get air out the other side, with no power connected to it, I'd say it's bad. The stepper motor on the end of it opens the valve by the EEC giving it a certain 'duty cycle'. If it's stuck open, it's like a huge vacuum leak into the engine. I'd replace it, check for any other vacuum leaks, and reset the EEC (Click here to see how to reset idle correctly). The check engine light usually comes on when an on-demand code is set, like if there's a hard fault. I pull my codes for the hell of it every couple weeks. Like said above, check the EGR valve, too. There should be no vacuum (or barely detectable) at the EGR valve at idle. This is why it's pointless to disable EGR: it only opens (controlled by computer again) at cruising speeds. Never at idle, never at WOT, and never while cold. Oh well, hope I gave you some ideas. Good luck.

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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch

LX XLR8R · 03-19-2001, 10:57 AM

wekk i dont use either on eiher of my stangs..once you get into some mods they seem to be more of a PITA..i made block off plates(EGR and AIB) for mine and i set the idle by the screw manually..works for me..just doesnt idle perfect in below freezing weather till its warm

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1987 black notch(ex 4 banger)
DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..
AIM=onesillynotch

QuantumMotorsports · 03-19-2001, 11:47 AM

If you don't find any vacuum leaks, try this. If the engine will idle high one day and not the next, or it idles high until you turn the engine off and start it again, you might have an electrical prob. Try this, while it is idling high, pop the hood and unplug the IAB valve. If the engine idles low when you unplug it, you know it's not a vacuum leak because the computer is intentionally opening that valve(or the valve is dirty and needs cleaning). If it idles low when IAB is unplugged try setting your TPS. If you've set your TPS and it still idles high, check wiring connections.(two big connectors behind intake, they should be cleaned) I had a bad ground to my TPS for a while and it caused my idle to stay high randomly. Cleaned the connectors and it helped, finally I ran new wires for the TPS and it works great now.

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Michael Black
Quantum Motorsports
Norman, Oklahoma

1988 Merc Cougar 5.0 HO, Ported and Polished E7TEs, 2.25" duals w/ 2 chamber flowmasters, T5 tranny
New E/T!!!
14.626 @ 94.94mph, 2.194 60' time, a little better than last time. Keep in mind this thang is heavy (3590lbs) Finally 14s!!!!

[This message has been edited by QuantumMotorsports (edited 03-19-2001).]

Green92LX · 03-19-2001, 01:08 PM

Try cleaning your 10-pin connector...solved my problem on my coupe...

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1992 5.0 LX, V-1 S-Trim @8LBS,Edelbrock 6037 Heads,Cobra Intake,E-303,1.6 Roller Rockers,65MM Holley TB, 75 MM Pro M Mass Air, 190 LPH FP,24 lb injectors,MSD 6A and BTM,BBK equal length shorties,offroad h-pipe,Mac Flowpath Mufflers,Pro 5.0, 3.73's,Motorsport "C" springs,welded subframe connectors,Ponies w/ 225/50 Nitto NT 450's on front,255/50 BFG Drags out back,93 Cobra Spoiler
Daily driver: 89 Coupe with 208K plus, BBK shorties,offroad h-pipe,2-chamber flowmasters with dumps,

03-18-2001, 09:55 PM	#1
Saleen308 Registered Member Join Date: Apr 2000 Location: Houston, Texas Posts: 142	Questions about IAB and EGR -------------------------------------------------------------------------------- I am in the process of trying to find out why my car idles so high. I am slowly trying to eliminate potential problems. Does the vacuum hose on the back of the EGR have a certain amount of vacuum at idle? I hooked my gauge up to it and it wouldn't register any thing. I put my finger over the end of the hose and I could just barely feel any vacuum . I checked my IAB(I guess that is what that thing is called that mounts on the side of the TB). It was clean. I blew air into one side of it and could feel air coming out the other side. Is this normal? ------------------ 347 stroker, TFS track heat heads ported and polished, ported GT-40 intake,70mm TB ans spacer,75mm MAF,K&N,24lb injectors,1 5/8" mac long tubes, off road h-pipe, FMS "z" cam, FMS plug wires, NGK plugs, FMS aluminum drive shaft, Omega 1.6 RR, FMS 3 core radiator, Flowkooler waterpump, World class T5, Pro 5.0 shifter, Autometer Fuel psi gauge, Autometer A/F gauge, caster camber plates, Koni reds, Pan hard bar, S.S. brake lines, Centerforce Dual Friction clutch, Walbro 255lph FP, Lakewood drivesha

03-18-2001, 10:28 PM	#2
vkaro45 Registered Member Join Date: Jul 2000 Location: Stafford, VA Posts: 54	The EGR doesn't have vacuum at idle so that seems to be ok. I'm not sure what you mean on the second part but there is a passage through the IAB with a valve in it. Make sure timing is correct, adjust idle with the IAB disconnected, set the TPS. If this doesn't work you could have a vacuum leak. Have you checked for codes? ------------------ '89 GT work in progress '66 289 coupe even more work

03-18-2001, 10:48 PM	#3
Saleen308 Registered Member Join Date: Apr 2000 Location: Houston, Texas Posts: 142	The check engine light is not on. Doesn't it have to be on to create a code to try and retrieve? ------------------ 347 stroker, TFS track heat heads ported and polished, ported GT-40 intake,70mm TB ans spacer,75mm MAF,K&N,24lb injectors,1 5/8" mac long tubes, off road h-pipe, FMS "z" cam, FMS plug wires, NGK plugs, FMS aluminum drive shaft, Omega 1.6 RR, FMS 3 core radiator, Flowkooler waterpump, World class T5, Pro 5.0 shifter, Autometer Fuel psi gauge, Autometer A/F gauge, caster camber plates, Koni reds, Pan hard bar, S.S. brake lines, Centerforce Dual Friction clutch, Walbro 255lph FP, Lakewood drivesha

03-18-2001, 11:22 PM	#4
vkaro45 Registered Member Join Date: Jul 2000 Location: Stafford, VA Posts: 54	No, my Lincoln T/C (same setup) had a bad egr valve. Pulled a code 34 but no check engine light. The diaphram was leaking causing a vacuum leak.

03-19-2001, 09:30 AM	#5
Capri306 Moderator Join Date: Sep 1998 Location: Grand Rapids, Michigan, USA Posts: 1,001	If you were able to blow air into one side of the IAB and get air out the other side, with no power connected to it, I'd say it's bad. The stepper motor on the end of it opens the valve by the EEC giving it a certain 'duty cycle'. If it's stuck open, it's like a huge vacuum leak into the engine. I'd replace it, check for any other vacuum leaks, and reset the EEC (Click here to see how to reset idle correctly). The check engine light usually comes on when an on-demand code is set, like if there's a hard fault. I pull my codes for the hell of it every couple weeks. Like said above, check the EGR valve, too. There should be no vacuum (or barely detectable) at the EGR valve at idle. This is why it's pointless to disable EGR: it only opens (controlled by computer again) at cruising speeds. Never at idle, never at WOT, and never while cold. Oh well, hope I gave you some ideas. Good luck. ------------------ Capri306, Moderator, The Mustang Works Online 1979 Mercury Capri, 5.0L -- C4 -- 2.73 1987 Mustang LX Notch

03-19-2001, 10:57 AM	#6
LX XLR8R Dirk Diggler Join Date: Feb 1999 Location: SLOATSBURG, NY Posts: 1,931	wekk i dont use either on eiher of my stangs..once you get into some mods they seem to be more of a PITA..i made block off plates(EGR and AIB) for mine and i set the idle by the screw manually..works for me..just doesnt idle perfect in below freezing weather till its warm ------------------ 1987 black notch(ex 4 banger) DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one.. AIM=onesillynotch

03-19-2001, 11:47 AM	#7
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	If you don't find any vacuum leaks, try this. If the engine will idle high one day and not the next, or it idles high until you turn the engine off and start it again, you might have an electrical prob. Try this, while it is idling high, pop the hood and unplug the IAB valve. If the engine idles low when you unplug it, you know it's not a vacuum leak because the computer is intentionally opening that valve(or the valve is dirty and needs cleaning). If it idles low when IAB is unplugged try setting your TPS. If you've set your TPS and it still idles high, check wiring connections.(two big connectors behind intake, they should be cleaned) I had a bad ground to my TPS for a while and it caused my idle to stay high randomly. Cleaned the connectors and it helped, finally I ran new wires for the TPS and it works great now. ------------------ Michael Black Quantum Motorsports Norman, Oklahoma 1988 Merc Cougar 5.0 HO, Ported and Polished E7TEs, 2.25" duals w/ 2 chamber flowmasters, T5 tranny New E/T!!! 14.626 @ 94.94mph, 2.194 60' time, a little better than last time. Keep in mind this thang is heavy (3590lbs) Finally 14s!!!! [This message has been edited by QuantumMotorsports (edited 03-19-2001).]

03-19-2001, 01:08 PM	#8
Green92LX Registered Member Join Date: Jun 1999 Location: North Haven,CT Posts: 336	Try cleaning your 10-pin connector...solved my problem on my coupe... ------------------ 1992 5.0 LX, V-1 S-Trim @8LBS,Edelbrock 6037 Heads,Cobra Intake,E-303,1.6 Roller Rockers,65MM Holley TB, 75 MM Pro M Mass Air, 190 LPH FP,24 lb injectors,MSD 6A and BTM,BBK equal length shorties,offroad h-pipe,Mac Flowpath Mufflers,Pro 5.0, 3.73's,Motorsport "C" springs,welded subframe connectors,Ponies w/ 225/50 Nitto NT 450's on front,255/50 BFG Drags out back,93 Cobra Spoiler Daily driver: 89 Coupe with 208K plus, BBK shorties,offroad h-pipe,2-chamber flowmasters with dumps,