Surging When Warm A9L Upgrade

killerbrd · 10-30-2006, 07:37 PM

Hello All! I am working with an 87 gt hatch. all bolt on upgrades..
BBK equal length headers, hi flow (no cat) H-pipe, flowmasters
stock motor, heads etc.... i did the mass air upgrade, and ever since when it is cold it runs like a dream. 10 minutes later, (or when i believe it is warmed up) it runs like balls. I just tuned it up with msd wires, platinum plugs, msd cap and rotor, set timing, and replaced the coolant sensor. nothing seems to solve it. any suggestions? O2 sensors? I was told to pull the pin on the distributor (that you disconnect when you set timing.) Bad Comp? It is the a9l computer. i have even removed the battery.....and then reconnected and ran it. Any help is greatly appreciated

mustangII460 · 10-30-2006, 07:39 PM

Check for codes.

Also check the TPS voltage.

killerbrd · 10-30-2006, 07:41 PM

What is the correct TPS voltage at idle for the A9l comp? I was foolin with that but never did put my voltmeter on it

93svt · 10-30-2006, 10:21 PM

Your throttle body and/or idle air control could be dirty. Maybe wierd coincidence?

Jeff Chambers · 10-31-2006, 08:02 AM

Its either lean or has too much timing at idle.

Dark_5.0 · 10-31-2006, 03:16 PM

Mine used to do the same thing and it was the O2 sensors. After they would warm up and kick in the car would surge.

I changed them and it was all good.

Good luck,

10-30-2006, 07:37 PM	#1
killerbrd Registered Member Join Date: Oct 2006 Posts: 4	Surging When Warm A9L Upgrade Hello All! I am working with an 87 gt hatch. all bolt on upgrades.. BBK equal length headers, hi flow (no cat) H-pipe, flowmasters stock motor, heads etc.... i did the mass air upgrade, and ever since when it is cold it runs like a dream. 10 minutes later, (or when i believe it is warmed up) it runs like balls. I just tuned it up with msd wires, platinum plugs, msd cap and rotor, set timing, and replaced the coolant sensor. nothing seems to solve it. any suggestions? O2 sensors? I was told to pull the pin on the distributor (that you disconnect when you set timing.) Bad Comp? It is the a9l computer. i have even removed the battery.....and then reconnected and ran it. Any help is greatly appreciated

10-30-2006, 07:39 PM	#2
mustangII460 Factoy Five Roadster Join Date: May 2000 Location: Sevier Co,Tennessee Posts: 1,681	Re: Surging When Warm A9L Upgrade Check for codes. Also check the TPS voltage. __________________ Frank

10-30-2006, 07:41 PM	#3
killerbrd Registered Member Join Date: Oct 2006 Posts: 4	Re: Surging When Warm A9L Upgrade What is the correct TPS voltage at idle for the A9l comp? I was foolin with that but never did put my voltmeter on it

10-30-2006, 10:21 PM	#4
93svt Registered Member Join Date: Aug 2006 Location: Yankton SD Posts: 27	Re: Surging When Warm A9L Upgrade Your throttle body and/or idle air control could be dirty. Maybe wierd coincidence?

10-31-2006, 08:02 AM	#5
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: Surging When Warm A9L Upgrade Its either lean or has too much timing at idle. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

10-31-2006, 03:16 PM	#6
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	Re: Surging When Warm A9L Upgrade Mine used to do the same thing and it was the O2 sensors. After they would warm up and kick in the car would surge. I changed them and it was all good. Good luck, __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

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