Hard starting when cold
#1
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Hard starting when cold
ok, i've got some time on my hands and i'm getting serious about finding the cause of my hard starting when cold problem.
Problem: turn key to ign, fuel pump primes, turn to run, cranks healthy, fires, stumbles, dies. crank again, fires, stumbles, dies again. I can keep it running if i give it gas. Runs great when it's warmed up. I've had this problem since i did my 350/T5 swap. got custom PROM made by tuned performance. converted sensors, ESC, all others i had to change over to 350 specific parts.
So today i hooked the car up to my computer and took some live data with tunerpro RT. i'm going to share 4 screen shots with you. based on what i saw on the live data when the car was warming up i have a few ideas. Please tell me what you think:
1) MAF sensor: when car is off or not running, it reads 23. When running at operating temperature, it reads hight 6s, low 7s. My FSM says that its supposed to read between 4-7 at idle when warmed up. if it's going over 7 does it mean it's bad? no codes set. It IS kind of old. probably over 15 years old.
2) The "desired idle" speed is set to 3187. why so high? is this correct?
3) CTS and TPS are both reading correctly. CTS read coolant temp accurately. Checked TPS with ignition on and checked the voltage reading as i pushed the gas pedal all the way down slowly. voltage at idle is .57 and smoothly went up. no jumping.
4) The live data has a section that says whether the engine is running lean or rich. I noticed it runs lean at start up, but once it gets warmed up it gets rich. shouldn't it be the opposite? could this be because of the MAF sensor?
So the only thing i can see that's wrong so far is the MAF is marginally out of spec due to it's live data readings. I REALLY want to make sure it's bad because this part isn't cheap (aftermarket brands are between $180 and $250, and brand new AC delco is $450!). TPI gurus i need your help!
Also, my photo-hosting website just went down for maintenance, so i will post my data screen shots when it comes back online.
Problem: turn key to ign, fuel pump primes, turn to run, cranks healthy, fires, stumbles, dies. crank again, fires, stumbles, dies again. I can keep it running if i give it gas. Runs great when it's warmed up. I've had this problem since i did my 350/T5 swap. got custom PROM made by tuned performance. converted sensors, ESC, all others i had to change over to 350 specific parts.
So today i hooked the car up to my computer and took some live data with tunerpro RT. i'm going to share 4 screen shots with you. based on what i saw on the live data when the car was warming up i have a few ideas. Please tell me what you think:
1) MAF sensor: when car is off or not running, it reads 23. When running at operating temperature, it reads hight 6s, low 7s. My FSM says that its supposed to read between 4-7 at idle when warmed up. if it's going over 7 does it mean it's bad? no codes set. It IS kind of old. probably over 15 years old.
2) The "desired idle" speed is set to 3187. why so high? is this correct?
3) CTS and TPS are both reading correctly. CTS read coolant temp accurately. Checked TPS with ignition on and checked the voltage reading as i pushed the gas pedal all the way down slowly. voltage at idle is .57 and smoothly went up. no jumping.
4) The live data has a section that says whether the engine is running lean or rich. I noticed it runs lean at start up, but once it gets warmed up it gets rich. shouldn't it be the opposite? could this be because of the MAF sensor?
So the only thing i can see that's wrong so far is the MAF is marginally out of spec due to it's live data readings. I REALLY want to make sure it's bad because this part isn't cheap (aftermarket brands are between $180 and $250, and brand new AC delco is $450!). TPI gurus i need your help!
Also, my photo-hosting website just went down for maintenance, so i will post my data screen shots when it comes back online.
#2
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
Screen shots. Just a heads up, I took these screen shots after 5-10 minutes of idling and then turned the car off (as you can probably tell from some of the data). i will take more screen shots tomorrow while the car is running.
also, i want to bring attention to a parameter in the 2nd picture. you will see the MAP parameter highlighted. My car does not have a MAP sensor and the value next to the parameter was changing. how can this be?
also, i want to bring attention to a parameter in the 2nd picture. you will see the MAP parameter highlighted. My car does not have a MAP sensor and the value next to the parameter was changing. how can this be?
#5
Supreme Member
iTrader: (2)
Re: Hard starting when cold
Are you running a 88 tune or did Tunedperformance migrate you onto a 89+? I ask as it may or may not be related to your cold start injector. If tuned did a 89 tune he would have allowed for 8 injectors to add fuel when cold. If he didn't- is your 9th injector all hooked up?
#6
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
He migrated me to an 89+ tune, because my engine is from a 1991 corvette and doesn't have a cold start injector.
Trending Topics
#9
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
can someone at least tell me what brand of MAF sensor works good for them? should i get another bosch? new or reman? where does everyone buy their MAFs from?
#11
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
Thanks for the suggestion! However, this isn't going to work for me because 1) there are no O'reilly auto part stores in NJ. 2) i went to their website to see if i could have on delivered and all they show is the A1 cardone garbage reman sensors. i'll do a search for rich-porter brand.
#12
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
what's the community's consensus on Spectra brand MAFs? That's the only brand i found that sells new units. Otherwise rock auto has reman'd AC delco units. that's probably the only reman'd brand i'd trust to use.
#13
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
bump. still need help.
#15
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
So before starting for the first time today, i primed the fuel system 4 times with the key and disconnected the EST wire. The engine fired and stayed on but idled very low. about 250 RPM. kept feathering the gas pedal for a few minutes. then turned the car off, reconnected the EST wire, started up, Idled better. Does this mean the pick up coil is bad?
#16
Senior Member
iTrader: (2)
Join Date: Aug 2014
Location: Fort Collins, CO
Posts: 575
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1991 Firebird Formula
Engine: 5.7L TPI
Transmission: 700r4
Axle/Gears: 3.23
Re: Hard starting when cold
Seems kind of strange that the IAC is pegged at 160 in your screenshots. Have you verified that it is functioning correctly? It may explain your extremely low idle if it's malfunctioning. When was the last time you checked the timing?
EDIT: Scratch that, I thought it was while it was running. 160 is normal for data when the engine is off, if I remember correctly. Unless it actually is running in the screenshots.
EDIT: Scratch that, I thought it was while it was running. 160 is normal for data when the engine is off, if I remember correctly. Unless it actually is running in the screenshots.
#17
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
yeah sorry. I have to get a screen shot when its running. also my timing is set at 8*. I'm not sure what it's set at on the chip itself. also, bought 2 brand new IACs. no change.
Last edited by GTAman; 09-09-2015 at 05:38 PM. Reason: adding info.
#18
Senior Member
iTrader: (2)
Join Date: Aug 2014
Location: Fort Collins, CO
Posts: 575
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1991 Firebird Formula
Engine: 5.7L TPI
Transmission: 700r4
Axle/Gears: 3.23
Re: Hard starting when cold
I've got a special interest in this thread since my car is having similar behavior, where it will catch and die a couple times when cold before starting. I've got a MAP, but hopefully I can get something out of the answers here. In case it's applicable, I also have working CTS and air intake temp sensors etc etc.
It does seem very strange that it was idling that low with EST disconnected. Did you read that 250 RPM from the scanner or just guess by sound? And dumb question, but good to rule everything out: You set the timing with the EST disconnected right? Have you been able to check fuel pressure while trying to start cold?
It does seem very strange that it was idling that low with EST disconnected. Did you read that 250 RPM from the scanner or just guess by sound? And dumb question, but good to rule everything out: You set the timing with the EST disconnected right? Have you been able to check fuel pressure while trying to start cold?
#19
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
cool. hopefully we can help each other out.
it was idling at 250 RPM based on what the Tach was showing. Engine was bogged down real low by the sound of it too. I did this because my FSM says to do this to test the distributor pick up coil.
Yes, i timed it with the EST wire disconnected at operating temperature. Keep in mind i started the engine with the EST wire disconnected when it was stone cold. so there was no advancement.
Fuel pressure cold at first start of the day is 42 PSI. I set it there with my AFPR.
It runs great when its warmed up, it just idles low when cold. like its not getting enough fuel enrichment or idle up. i wish i had my EBL flash ECM. That's next on the list.
it was idling at 250 RPM based on what the Tach was showing. Engine was bogged down real low by the sound of it too. I did this because my FSM says to do this to test the distributor pick up coil.
Yes, i timed it with the EST wire disconnected at operating temperature. Keep in mind i started the engine with the EST wire disconnected when it was stone cold. so there was no advancement.
Fuel pressure cold at first start of the day is 42 PSI. I set it there with my AFPR.
It runs great when its warmed up, it just idles low when cold. like its not getting enough fuel enrichment or idle up. i wish i had my EBL flash ECM. That's next on the list.
#22
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
no ideas, huh? i know throwing parts at a car isn't the best way to go about diagnosis, but given the info i've presented, i'm going to pick up a cheap MAF sensor and see what that does. If it fixes the problem, i'll return it and buy a better one. If it doesn't the diagnosis will continue.
Until then, tune in next time for another post of "Hard starting when cold".
Until then, tune in next time for another post of "Hard starting when cold".
#24
Senior Member
iTrader: (1)
Join Date: Dec 2012
Location: Western NY
Posts: 629
Likes: 0
Received 2 Likes
on
2 Posts
Car: 88 convertible
Engine: 5.7L
Transmission: 4+3 maual
Axle/Gears: 3.07
Re: Hard starting when cold
no ideas, huh? i know throwing parts at a car isn't the best way to go about diagnosis, but given the info i've presented, i'm going to pick up a cheap MAF sensor and see what that does. If it fixes the problem, i'll return it and buy a better one. If it doesn't the diagnosis will continue.
Until then, tune in next time for another post of "Hard starting when cold".
Until then, tune in next time for another post of "Hard starting when cold".
Why such a low idle? Did you set the minimum idle speed via the throttle blade stop screw? What are your IAC steps when idling?
#25
Senior Member
Thread Starter
iTrader: (2)
Join Date: Jan 2003
Location: Northern New Jersey
Posts: 640
Received 0 Likes
on
0 Posts
Car: 1988 Trans am GTA
Engine: corvette 350 swap
Transmission: t-5 swap
Axle/Gears: 3.27:1 borg warner 9-bolt w/ PBRs
Re: Hard starting when cold
So tonight i took the car out for the first time since doing the head gaskets. Drove it all night. I tried starting it with the MAF disconnected, didn't want to start. Plugged it back in and fired up. So the MAF is good?
Again, once warmed up she ran like a champ! drove 50 miles and she used a quarter of a tank. not too bad.
Actually here's a stupid question: I disconnect the battery every time i put the car back in the garage. would this cause the hard starting?
#26
Senior Member
iTrader: (3)
Join Date: Jan 2012
Location: Clark NJ
Posts: 877
Likes: 0
Received 2 Likes
on
2 Posts
Car: 1988 Pontiac Transam GTA Notchback
Engine: 2003 Chevy 5.3 Vortec (325 cu)
Transmission: 4L60E
Axle/Gears: 3.27
Re: Hard starting when cold
Well it doesnt help. Everytime you disconnect the battery and reconnect, the computer has to relearn itself. Leave it connected and see what happens.
Thread
Thread Starter
Forum
Replies
Last Post