Car hard starting hot...help

Nasty_Notch · Oct 18, 2006

I have just developed a hard start condition when car is warm/hot.will crank but not start unless I put pedal to the floor.Smells like it's running rich when
at idle.Combo has been together for about 3 weeks & has run perfect.I tried to pull codes last night using test light & jumper wire but it didn't work although I'm not sure if I'm doing it right.Test light just stays solid when trying to pull codes. Any suggestions would be appreciated.Car starts & runs fine when started cold.
Rob
Note,just for **** & giggles,I unplugged IAC with car running & idle did not change at all.

jrichker · Oct 18, 2006

Dump the codes and see what the computer says is wrong… Codes can be present without setting the Check Engine Light.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.

WalMart may have the above LCD display scanner for less than $35.

Look for code 21 being set - it is an ECT fault that is associated with hot start problems

If you cannot dump the codes, repost and I will try to help. there are some speific checks that will locate the fault that is preveting the codes from being dumped. It is very seldom a problem with the computer itself, usually the wiring is the cause.

Nasty_Notch · Oct 18, 2006

Too funny,I actually searched for some of your posts last night when at home.I followed instructions using test light & the light just stayed solid.My multi-meter is digital so thats no help.The check engine light is currently on.
I suspect the ECT by the symptoms but I would rather diagnose it than throw parts at it.
Thank you for your reply.

jrichker · Oct 18, 2006

Computer will not go into diagnostic mode

With the power off, measure the resistance between the computer test ground
(black/white wire) on the self test connector and battery ground. You should see less than
1.5 ohms.

If that check fails, remove the passenger side kick panel and disconnect the computer
connector. There is a 10 MM bolt that holds it in place. Measure the resistance between
the black/white wire and pin 46: it should be less than 1.5 ohms. More that 1.5 ohms is a
wiring problem. If it reads 1.5 ohms or less, then the computer is suspect. On the
computer, measure the resistance between pin 46 and pins 40 & 60: it should be less than
1.5 ohms. More that that and the computer’s internal ground has failed, and the computer
needs to be replaced.

If the first ground check was good, there are other wires to check. Measure the
resistance between the STI computer self test connector (red/white wire) and pin 48 on
the computer main connector: it should be less than 1.5 ohms. More that 1.5 ohms is a
wiring problem

The following is a view from the computer side of the computer connector.

Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine

The ECT uses the same signal ground (black/white wire) as the computer test. Find & fix
one problem and you migh get the other one fixed at the same time.

Nasty_Notch · Oct 18, 2006

Thank you for the extensive info.I will try this tonight when I get home & keep post updated.
Rob
Edit,looks like I'm gonna take home my shop's Snap-on scanner & try to pull codes that way 1st.

Nasty_Notch · Oct 19, 2006

Well I tried to pull codes with pos Snap-on scanner last night,scanner is junk.It wouldn't even power up.Car won't even stay running now.Starts & runs for about 30 seconds & then dies out like running out of fuel.Fuel pressure stays steady 39-40 on guage when this happens.Meter is a PRO-M
That is about 3 weeks old.I went through & checked all connections..salt & pepper,IAC,MAF,ECT,etc.Was so pissed off it wouldn't run I shut the hood before I took a hammer to it.I've got a wake to go to tonight so I'll try again tomorrow night.

jrichker · Oct 19, 2006

Did you go all the way through the computer won't go into diagnostic mode tech note I posted?

Nasty_Notch · Oct 19, 2006

jrichker said:
Did you go all the way through the computer won't go into diagnostic mode tech note I posted?

I did not get that far.I got home from work late last night & just figured I'd try scanner & a couple simple things.But now that the car won't stay running I'l have to follow your diag chart.
Thanks,
Rob

Nasty_Notch · Oct 19, 2006

Well,one problem has been diagnosed.In my fumbling around to try to pull codes,I must have "powered up" signal return wire & fried internal ground in computer. Car has 13 codes all related to ground side of sensors Egr, Maf,Ect,Act,Tps...Does anybody have a spare computer for sale????Is model # on side of computer ie: AL9
That will get the car running but I will still have to diag hard start when it runs.What a moron.

Nasty_Notch · Oct 19, 2006

Well,one problem has been diagnosed.In my fumbling around to try to pull codes,I must have "powered up" signal return wire & fried internal ground in computer. Car has 13 codes all related to ground side of sensors Egr, Maf,Ect,Act,Tps...Does anybody have a spare computer for sale????Is model # on side of computer ie: AL9
That will get the car running but I will still have to diag hard start when it runs.What a moron.
Sorry bout the double post

Nasty_Notch · Oct 26, 2006

Well,new computer is in & car runs...thats the good news.Bad news is it's running pig rich,blowing black smoke.CEL is on,has hard faults of Map sensor & canister purge solenoid high voltage.Maf & ect sensor high voltage in memory.I went through flow chart from Alldata to diag Map sensor & says "plug in Map sensor tool" which I don't have.I'm gonna check wiring to cannister purge solenoid to make sure it's not wrapped around alternator/header tube lol.
I'm just bummed out.I have had car running with blower for about 2 weeks...

HISSIN50 · Oct 26, 2006

Is the MAP sensor vac line plugged in?

If not, it will run super rich and idle like crap.

I think JR just posted some info on another thread about testing the MAP sensor electrical side of things - he will probably repost that info here.

Good luck.

stangjunkie · Oct 26, 2006

i want a million dollars.... (well it was working for everyone else)

Nasty_Notch · Oct 27, 2006

HISSIN50 said:
Is the MAP sensor vac line plugged in?

If not, it will run super rich and idle like crap.

I think JR just posted some info on another thread about testing the MAP sensor electrical side of things - he will probably repost that info here.

Good luck.

I will double check that this weekend,thank you.

jrichker · Oct 27, 2006

Post the EXACT codes you got. There may still be some signal ground problems causing your codes & poor performance.

One of the things that will kill the MAP operation is a bad ground.

Code 22 MAP (vacuum) or BARO signal out of range. The MAP or BARO sensor is pretty much the same sensor for both Mass Air & Speed Density cars. The main difference is where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the air/fuel mixture by sensing changes in barometric pressure. The MAP or BAP sensor puts out a 5 volt square wave that changes frequency with variations in atmospheric pressure. The base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees. You need an oscilloscope or frequency meter to measure it. There is no way you can use a common cheap voltmeter or DVM to accurately measure the output signal.

The MAP/BARO sensor is mounted on the firewall behind the upper manifold.

Baro or MAP test using frequency meter - run the test key on engine off. The noise from the ignition system will likely upset the frequency meter. I used a 10 x oscilloscope probe connected from the frequency meter to the MAP/BAP to reduce the jitter in the meter's readout.

If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer

Some basic checks you can make to be sure that the sensor is getting power & ground:
Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.
Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery cable. It should be less than 1.5 ohm.

The following power on check requires you to turn the ignition switch to the Run position.
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or EGR sensors. Use the black/white wire for the ground for the DVM.

Nasty_Notch · Oct 27, 2006

Codes are as follows
Hard faults
22 Baro/Map sensor out of self test range
85 Cannister purge circuit failure..could care less about this one
memory codes
22 again
66 Maf circuit below minimum voltage.
Thanks for info JRICHKER
I will concentrate on 22 for now...

Nasty_Notch · Nov 2, 2006

Minor update,Map sensor failed pinpoint test.I have one on order,will keep updated.

Nasty_Notch · Nov 3, 2006

Map sensor installed,car still blowing black smoke.Code 66 came back.I smoked my 3 week old $320.00 Prom-m meter.New meter on order from Anderson,eta is Tuesday or Wednesday.I'm also putting an Iac on while I'm at it.Had code for can't control idle,Iac will not respond.I also still have to diag original problem of hard start hot when car is up & running right.What a month... I feel like I'm gonna throw up.... One thing that I found weird was that when I ordered new Maf,they only wanted to know what size injectors.They said it didn't matter that it's a boosted motor or a running power pipe etc. 1st one I oredred locally & I had to give them all particulars on my combo.

Nasty_Notch · Nov 16, 2006

Well,the car is up & running with new MAF.Runs & drives fine but still has hard start hot problem.No codes except 85 which I don't care about.When I get some $$$ I'll get it dyno-tuned & chip burnt.What a @*&^%$#@ nightmare.

jrichker · Nov 16, 2006

Nasty_Notch said:
Well,the car is up & running with new MAF.Runs & drives fine but still has hard start hot problem.No codes except 85 which I don't care about.When I get some $$$ I'll get it dyno-tuned & chip burnt.What a @*&^%$#@ nightmare.

Since you are now able to dump codes, your signal ground for the sensors and code dump must be OK. I would recommend that you spend the $13-$15 for a new ECT. That will probalby fix your hot start problems.

Car hard starting hot...help

New Member

StangNet's favorite TOOL

New Member

StangNet's favorite TOOL

New Member

New Member

StangNet's favorite TOOL

New Member

New Member

New Member

New Member

"How long does it take to get help in here?

New Member

New Member

StangNet's favorite TOOL

New Member

New Member

New Member

New Member

StangNet's favorite TOOL

Similar threads

Privacy & Transparency

Privacy & Transparency