Help with cold start

Does the car have the factory H pipe on the exhaust?

Could be that that passenger side has a lean cylinder. Have you shot the headers right at the cylinder head to make sure you are not running lean on a cylinder? Another thing to do is check for codes. Check engine light (CEL) only illuminates with emissions related codes so other codes can exist with no CEL light.

Clogged or improperly working.

You may need to do a fuel pressure check and make sure the fuel pressure is consistent with key on and when engine is running also driving.

A bad fuel filter or a faulty fuelpump relay could cause the issues youre experiencing so can dirty connector pins at the salt n pepper shaker connects that control the fuel injectors and send readings to the ECU from the sensors..........

Most times an issue like yours can be related to an airleak anywhere in the system............A DIY smoke machine or a cigar will do the trick and tell you where every leak is as those vacuum tree lines are highly prone to cracking.....

A bad coolant temp or air temp sensor could be giving the wrong temp & could be the culprit too.........

Even a faulty TPS can throw a lean code just like advancing the distributor too far too.........

Putting a bigger throttlebody or a bigger MAF or modifying the inlet tube or relocating the aircharge temp sensor into the intake can cause huge issues too..

What I do is start with the basics like verifying the MAF is working as the engine load is determined by what the MAF reads...

What most dont know is with a Mustang computer is you can use an adapter wire to connect the car up to an OBD2 scanner or you can get an OBD2 scanner that also can read OBD1 codes so you can read live data .............





Its great to see everything thats going on while the engine is operating..................



To rule out the O2 sensors I first make sure that the ground wire coming off pin #49 is hooked to the intake manifold and I verify its grounded good then remove them from the car and clean them in straight lemon juice for 20-25 mins then rinse with rubbing alcohol then blowdry with air...

Another thing to note is if you disconnected the EGR and dont have a shunt or resistors or a tuning chip to trick or turn off the EGR you wont get any spark advance too and will stay locked at 30* of timing as a default variable because the lil electrical doo-dad is a potentiometer mounted on top of the vacuum diaphragm and tells the computer whether to advance or retard the ignition depending on vacuum signal and Pin position plus BAP reading.................









Theres 2 methods to disabling the EGR Im partial to and one is the chip and the other is just by blocking off the EGR port with a simple blockoff gasket and letting the EGR do its thing without injecting dirty air into the intake stream but if youre set on using the resistors buying a wideband controller and using the EGR pin to control lambda would be a good idea................

Another downside to doing the EGR delete is engine detonation if premium 93 octane or higher isnt used,,,,,,,,,,,,,,,,,,

It literlly took 5 mins to disable the EGR on this 351w using a piece of self sticking foil tape over the hole and reinstalling the EGR............



As you can see from this picture this is how to block them off fast n easy then reinstall the diaphragm and sensor.....



I dont like doing the resistors because all they do is trick the CEL and spark advance is taken over by only the BAP throwing off calculations but can also incorporate the thermactor delete into the EGR resistor trick too............








Good Luck

Artemisia22 said:

Thanks for the information ! Luckily I still have my operating EGR, I think I may have an air leak somewhere and my diy smoke machine kinda combusts every time I try to use it (I’m using mechanics wire instead of rated wire). When I disconnect my MAF, the engine stutters and almost stalls but doesn’t. I have disconnected the IAC, but it didn’t skip a beat, which is kinda concerning but I’m not sure what that means.

Click to expand...

When the MAF fails the TPS and the BAP are supposed to take over and combine with a MAF fault table and when the TPS fails the value the computer gets on default is a constant 1.25 volts..



I have mine set to where my TPS is set to which is 0.82volts to get a more broader and linear TPS range when I utilized the blank cells by filling them in with actual values which also smoothes out the scaling tables a lil more in the MAF and the TPS settings to get smoother transition rates..

At idle my TPS is set to .082 and at WOT it shows 4.47volts....I had to reset my WOT off trigger almost a volt higher than the stock setting too....

Its annoying when I nailed the loud pedal and the momentum stayed consistent until I backed off the throttle to a lil under 5/8 pedal and then the vehicle started to respond and slow down.....Now I have it in the tad over 3/4 throttle back off range at 3.375 volts instead of 2.7750 volts.....

Who needs lean cruise mode when you have a hotrod...............LOL









In the sections labeled "value 2" is a comparison in the settings between my tune changes on the left in value 1 and and a stock A9L in value 2 and alls that was done was a 351w swap and a full emissions delete plus a 75mm MAF from a Thunderbird SC and a 70mm TB...........Oh and headders plus full MSD ignition system w/timing advance knob too also a wideband 02 controller.




What does the car do when you pull the spout connector out too?..It should stay running above stall in the 500-550rpm range and if not try getting it to barely run using the t-stop screw after verifying timing is set and locked in at 10* btdc and verify it doesnt waiver by bringing the rpm's up to 3-4000 rpm's..

I use a vacuum gauge to set my timing.......wherever I get max vacuum at idle is where I set it then I verify setting on the balancer with my timing gun then go back in the computer and make the changes to reflect those settings like timing setting and TPS position after idle speed is set so the computer can make the truuest calculations and corrections for efficient running aswell as making the best changes based on the engine + tune settings together......





Also try plugging in the MAF and disconnecting the TPS. The idle should kick up to atleast 1100rpm's.............

Another thing to note about setting idle....If you set it above the stock 672 a bunch of other variables need to be changed or everytime a flag gets set the idle changes and most who experience these changes called hysterics they fall into a trap of endlesly doing base idle resets along with battery bleed downs and hoping for the best..

If you dont change the base idle rpm's in the settings the computer just goes by the values set on the scaling tables a short time after driving and not responding much by the throttlestop setting anymore either and then when it cant correct or make sense of it all it goes into a mode called hysterysis where the idle shoots up to 1008rpm's over idle setting in the ECU meaning youll be experiencing over 1600rpm's of idle and would require a shutdown and a restart to regain control..........These 3 are just a few that need to be changed to reflect the change in rpm's and have the ECU do proper calculations



Good Luck in getting your ride sorted out and if all else fails see about sending your ECU out to be diagnosed and also upgraded with new capacitors and circuitry beef-ups that is done by most reputable refurbishers..............



The best part about the whole thing is if the ECU came out of the vehicle you own and not one bought on ebay the diagnoser can give you insight on the problem areas to look into before hooking up the ECU...............

Take care