Another hesitation under boost thread

Phinney · March 24th, 2011, 06:30 PM

Ive been driving the turbo around town today to get this engine driving smoothly. Biggest problem I have right now is the down elbow from the turbo is cracked, and my replacement is a few days away. There is a significant exhaust leak in the engine bay that causes a loud chugging noise. will be fixed soon.

When I drive the car easy, it accelerates smooth for a small 4 banger. If i give it some serious gas, the boost rises real quick to 18 psi, but ZERO change in RPM or acceleration. Its not like it hesitates or bogs, just no difference except it sounds like a diesel truck. I am wondering if the exhaust leak AFTER the turbo is causing this? Or if anyone can offer any other obvious things to check.

My wideband is not hooked up yet because I am waiting for my new exhaust to weld in the bung. Have a digital fuel pressure guage but I ordered the wrong adapter so that is out of order for now as well.

03 R Code · March 24th, 2011, 10:57 PM

Does it still have the factory O2 sensor? I would guess if there is a large leak before it it's sending a false signal to the ECU causing your problems.

Cgross609 · March 25th, 2011, 04:36 AM

If my memory is correct, there is a large crack in your manifold, mentioned in your thunderstang thread, but also, is there a leak after the turbo? My guess is the pressure difference inside the exhaust is causing the turbo to backspin or something along those lines... Truthfully i have no idea

i'm just some dumb kid that probably should keep his opinions to himself. But whatever. Its 2:34 in the morning here. So screw it. I hope that your new manifold will fix this problem!

Cgross609 · March 25th, 2011, 04:37 AM

*Ahem*... Not the fact that its 2:34am. Lol....

Phinney · March 25th, 2011, 09:30 AM

03 R code I think you may be right and I hadnt given that any thought.

Cgross I am still using that manifold, but I used some 2000 degree exhaust putty on the hairline cracks, and it seems to be holding because I can feel no air escaping. But yes, I am on the lookout for a new manifold as well.

I am going to look into the 02 sensor problem. Thanks!

OHC230 · March 25th, 2011, 12:09 PM

Phinney, a crack in the exhaust elbow, depending where it is, could cause exhaust gasses to bypass the integral waste gate. Even though you might see 18 psi at the boost gauge, you might still not see enough RPM at the turbo, to generate enough volume to run correctly. I am assuming that you still have the factory integral waste gate?

The O2 sensor would not make this much difference. Unplug it and see. What does the ignition timing look like on your car? Have you tried adjusting it recently? Advance it and see what happens, this too will have a huge affect on how your car accelerates. I can think of dozens of things to check here, but I need to get a vague idea of the history of your car.

So, this is Thunderstang were talking about?

Phinney · March 25th, 2011, 01:31 PM

When It firt started up I had the timing set at 18 BTDC. I tried it at around 14, and now it is right at 10 BTDC. Didnt notice much of a difference at the three settings. What would you reccomend i set it at? And yes I am still using the Integral wastegate.

I did pick up the t3/t4 turbo (which is huge!) but it is sitting on the shelf until I can get this car running smooth as it is.

Thunderstang!

OHC230 · March 25th, 2011, 03:45 PM

The short answer to that is, you want to run as much advance as you can, without detonation. That will be somewhere around 12-15 degress initial advance.

How new are the cap rotor and plugs?

Which turbo are you running now?

Which car are we talking about here, your T-bird, or are you driving the Mustang?

Phinney · March 25th, 2011, 03:50 PM

Still working on the 88 tbird with a stock IHI turbo. cap and rotor are motorcraft replaced ~1000 miles before rebuild.

Phinney · March 25th, 2011, 05:46 PM

Checked the timing, don't ask me how, but it had moved to 5 degrees ATDC... set it to 18 BTDC and away she went. Stronger than before, you can tell when boost kicks in, but I hear a lot of air coming out somewhere so I suspect boost leaks are everywhere in these old lines.

Shes getting better, slowly. Ill keep making improvements!

03 R Code · March 25th, 2011, 06:28 PM

I would back that timing off if you are making any sort of decent boost, you could likely blow a head gasket with that much timing and moderate boost.

ranger50toy · March 28th, 2011, 12:00 PM

Are you sure it is not the clutch slipping?

Phinney · March 28th, 2011, 02:28 PM

Yeah, the rpms don't rise so the clutch is not slipping. Also, its a brand new clutch replaced in the rebuild about 10 miles ago!

March 24th, 2011, 06:30 PM	#1
Phinney Regular 2004 Mustang Convertible Join Date: Apr 2009 Location: Fort Lauderdale, FL Posts: 156 iTrader: 0 reviews	Another hesitation under boost thread Ive been driving the turbo around town today to get this engine driving smoothly. Biggest problem I have right now is the down elbow from the turbo is cracked, and my replacement is a few days away. There is a significant exhaust leak in the engine bay that causes a loud chugging noise. will be fixed soon. When I drive the car easy, it accelerates smooth for a small 4 banger. If i give it some serious gas, the boost rises real quick to 18 psi, but ZERO change in RPM or acceleration. Its not like it hesitates or bogs, just no difference except it sounds like a diesel truck. I am wondering if the exhaust leak AFTER the turbo is causing this? Or if anyone can offer any other obvious things to check. My wideband is not hooked up yet because I am waiting for my new exhaust to weld in the bung. Have a digital fuel pressure guage but I ordered the wrong adapter so that is out of order for now as well. __________________ 2004 Convertible - SOLD 1999 Coupe - SOLD 1966 Coupe - SOLD 1987 TurboCoupe - Cut in prices! 1970 Coupe - Soon to be 140 Turbo! 1984 El Camino Conquista - moving truck 2011 Convertible V6 Base 2012 Coupe GT Premium 5.0 Baby!

March 24th, 2011, 10:57 PM	#2
03 R Code MM Fanatic unstoppable @ speed of light Join Date: Jul 2006 Location: Knees deep in dat ass Posts: 3,103 iTrader: 0 reviews	Does it still have the factory O2 sensor? I would guess if there is a large leak before it it's sending a false signal to the ECU causing your problems. __________________ Political correctness is a doctrine fostered by a delusional, illogical, liberal minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

March 25th, 2011, 04:36 AM	#3
Cgross609 Regular 93 Mustang LX 2.3 T-5 Join Date: Sep 2010 Location: Vegreville, AB Posts: 270 iTrader: 0 reviews	If my memory is correct, there is a large crack in your manifold, mentioned in your thunderstang thread, but also, is there a leak after the turbo? My guess is the pressure difference inside the exhaust is causing the turbo to backspin or something along those lines... Truthfully i have no idea i'm just some dumb kid that probably should keep his opinions to himself. But whatever. Its 2:34 in the morning here. So screw it. I hope that your new manifold will fix this problem! __________________ 93 2.3l LX U.S. 15x7 ten hole rims Calypso green Moates QH T-5 Conversion Dual 2.5" Exhaust with Thrush Welded muffler

March 25th, 2011, 04:37 AM	#4
Cgross609 Regular 93 Mustang LX 2.3 T-5 Join Date: Sep 2010 Location: Vegreville, AB Posts: 270 iTrader: 0 reviews	Ahem... Not the fact that its 2:34am. Lol.... __________________ 93 2.3l LX U.S. 15x7 ten hole rims Calypso green Moates QH T-5 Conversion Dual 2.5" Exhaust with Thrush Welded muffler

March 25th, 2011, 09:30 AM	#5
Phinney Regular 2004 Mustang Convertible Join Date: Apr 2009 Location: Fort Lauderdale, FL Posts: 156 iTrader: 0 reviews	03 R code I think you may be right and I hadnt given that any thought. Cgross I am still using that manifold, but I used some 2000 degree exhaust putty on the hairline cracks, and it seems to be holding because I can feel no air escaping. But yes, I am on the lookout for a new manifold as well. I am going to look into the 02 sensor problem. Thanks! __________________ 2004 Convertible - SOLD 1999 Coupe - SOLD 1966 Coupe - SOLD 1987 TurboCoupe - Cut in prices! 1970 Coupe - Soon to be 140 Turbo! 1984 El Camino Conquista - moving truck 2011 Convertible V6 Base 2012 Coupe GT Premium 5.0 Baby!

March 25th, 2011, 12:09 PM	#6
OHC230 Enthusiast Supercharged 89'/ 85' SVO 11.945 @ 119.6 Join Date: Jan 2010 Location: Napa Valley CA Posts: 879 iTrader: 0 reviews	Phinney, a crack in the exhaust elbow, depending where it is, could cause exhaust gasses to bypass the integral waste gate. Even though you might see 18 psi at the boost gauge, you might still not see enough RPM at the turbo, to generate enough volume to run correctly. I am assuming that you still have the factory integral waste gate? The O2 sensor would not make this much difference. Unplug it and see. What does the ignition timing look like on your car? Have you tried adjusting it recently? Advance it and see what happens, this too will have a huge affect on how your car accelerates. I can think of dozens of things to check here, but I need to get a vague idea of the history of your car. So, this is Thunderstang were talking about? __________________ Supercharged 2.7L 398 HP 501 ft lb !!

March 25th, 2011, 01:31 PM	#7
Phinney Regular 2004 Mustang Convertible Join Date: Apr 2009 Location: Fort Lauderdale, FL Posts: 156 iTrader: 0 reviews	When It firt started up I had the timing set at 18 BTDC. I tried it at around 14, and now it is right at 10 BTDC. Didnt notice much of a difference at the three settings. What would you reccomend i set it at? And yes I am still using the Integral wastegate. I did pick up the t3/t4 turbo (which is huge!) but it is sitting on the shelf until I can get this car running smooth as it is. Thunderstang! __________________ 2004 Convertible - SOLD 1999 Coupe - SOLD 1966 Coupe - SOLD 1987 TurboCoupe - Cut in prices! 1970 Coupe - Soon to be 140 Turbo! 1984 El Camino Conquista - moving truck 2011 Convertible V6 Base 2012 Coupe GT Premium 5.0 Baby!

March 25th, 2011, 03:45 PM	#8
OHC230 Enthusiast Supercharged 89'/ 85' SVO 11.945 @ 119.6 Join Date: Jan 2010 Location: Napa Valley CA Posts: 879 iTrader: 0 reviews	The short answer to that is, you want to run as much advance as you can, without detonation. That will be somewhere around 12-15 degress initial advance. How new are the cap rotor and plugs? Which turbo are you running now? Which car are we talking about here, your T-bird, or are you driving the Mustang? __________________ Supercharged 2.7L 398 HP 501 ft lb !!

March 25th, 2011, 03:50 PM	#9
Phinney Regular 2004 Mustang Convertible Join Date: Apr 2009 Location: Fort Lauderdale, FL Posts: 156 iTrader: 0 reviews	Still working on the 88 tbird with a stock IHI turbo. cap and rotor are motorcraft replaced ~1000 miles before rebuild. __________________ 2004 Convertible - SOLD 1999 Coupe - SOLD 1966 Coupe - SOLD 1987 TurboCoupe - Cut in prices! 1970 Coupe - Soon to be 140 Turbo! 1984 El Camino Conquista - moving truck 2011 Convertible V6 Base 2012 Coupe GT Premium 5.0 Baby!

March 25th, 2011, 05:46 PM	#10
Phinney Regular 2004 Mustang Convertible Join Date: Apr 2009 Location: Fort Lauderdale, FL Posts: 156 iTrader: 0 reviews	Checked the timing, don't ask me how, but it had moved to 5 degrees ATDC... set it to 18 BTDC and away she went. Stronger than before, you can tell when boost kicks in, but I hear a lot of air coming out somewhere so I suspect boost leaks are everywhere in these old lines. Shes getting better, slowly. Ill keep making improvements! __________________ 2004 Convertible - SOLD 1999 Coupe - SOLD 1966 Coupe - SOLD 1987 TurboCoupe - Cut in prices! 1970 Coupe - Soon to be 140 Turbo! 1984 El Camino Conquista - moving truck 2011 Convertible V6 Base 2012 Coupe GT Premium 5.0 Baby!

March 25th, 2011, 06:28 PM	#11
03 R Code MM Fanatic unstoppable @ speed of light Join Date: Jul 2006 Location: Knees deep in dat ass Posts: 3,103 iTrader: 0 reviews	I would back that timing off if you are making any sort of decent boost, you could likely blow a head gasket with that much timing and moderate boost. __________________ Political correctness is a doctrine fostered by a delusional, illogical, liberal minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

March 28th, 2011, 12:00 PM	#12
ranger50toy Regular 1988 2.3L Hatch Ha-Ha Join Date: Dec 2010 Location: Lansing Mi Posts: 99 iTrader: 0 reviews	Are you sure it is not the clutch slipping?

March 28th, 2011, 02:28 PM	#13
Phinney Regular 2004 Mustang Convertible Join Date: Apr 2009 Location: Fort Lauderdale, FL Posts: 156 iTrader: 0 reviews	Yeah, the rpms don't rise so the clutch is not slipping. Also, its a brand new clutch replaced in the rebuild about 10 miles ago! __________________ 2004 Convertible - SOLD 1999 Coupe - SOLD 1966 Coupe - SOLD 1987 TurboCoupe - Cut in prices! 1970 Coupe - Soon to be 140 Turbo! 1984 El Camino Conquista - moving truck 2011 Convertible V6 Base 2012 Coupe GT Premium 5.0 Baby!

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