Wont start, Started troubleshooting tonight

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boosteds10

Finally Fixed
I just bought a 93 ty a few weeks ago. It ran fine, needed a tune up . It had an erratic idle it would bounce from 700 to 1000 and looking at datamaster it was throwing an Iac malfunction. So I did cap, rotor, plugs and wires last weekend. Took it out fro a drive and it was great 15psi, very responsive, get it home and it wont start so I figured the iac finally gave out cuz it would run if I kept my foot on the gas and above 1000rpm.

So Just tonight I throw the new IAC in. Turn it over and it idles real low and dies. It threw a MAP High code so I cleared them all out and tried some more to no avail. Should I be chasing a vacuum leak? If I give it gas now it instnatly dies. or if it starts on its own, as soon as it fires and I get off the key it dies.

Sorry for the novel, just frustrated already with this truck :rotf:
 
K

KDBL1

New member
Re: Wont start, Started troubleshooting tonight

Try TPS , did you clear any stored codes during tune up by removing battery terminals or pulling ECM fuses. Try clearing codes by methods listed , start TY let ECM learn idle in Park ,Neutral , and Drive for about 1 minute in each gear selection. Don,t give it any gas let it reset the idle itself.
 
K

KDBL1

New member
Re: Wont start, Started troubleshooting tonight

They are alot of work but worth it when they are running right.
 
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boosteds10

Finally Fixed
Re: Wont start, Started troubleshooting tonight

Thanks guys, I had actually planned on takin today off to do all the work but I got a head start and managed to do some last night. Ill be out there all day tryin to get this runnin.

Tooky, I have read a decent amount of your site and it has helped a ton and given me a shove in the right direction for modding or not modding for that matter :tup:

Did the intercooler hoses and the iac last night. Today is kyb monomax all around, home made air intake, lo-tek gauge pod with boost, trans temp, and fuel pressure gauges, TCC switch and Intercooler pump hotwire.

Let you guys know how things went tonight
 
NecroWolf

NecroWolf

lost marbles member
Re: Wont start, Started troubleshooting tonight

its not mentioned often but there is a certain procedure for replacing the iac that rezeros the iac so the computer knows exactly where it is
 
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boosteds10

Finally Fixed
Re: Wont start, Started troubleshooting tonight

Necro, what procedure is this because I just pulled the iac back out and keyed the truck on, it doesnt move but when I put it into test mode, Pins A&B jumped it moves.
 
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boosteds10

Finally Fixed
Re: Wont start, Started troubleshooting tonight

I just checked the fuel pump relay, it clicks and the fuel pump primes, pump also runs for 2 seconds after I crank so I am pretty sure its good. Also checked for fuel on the rail at the schrader and its there.

Both ECU fuses are good. The only thing thats bothering me is the IAC count in datamaster is 167...i thought it only went to 100. I did the whole iac relearn thing and that didnt help.

Ill be checking for spark soon and after that im all out of ideas
 
Don W.

Don W.

Stab it and steer it
Re: Wont start, Started troubleshooting tonight

Don't fiddle with an old IAC. R&R is OK, just don't push on the pintle. You can mess them up. I'll see if I can find the info and get back.

Edit:

Per the manual you can damage the internal threads by pushing or pulling on the pintle. If re-installing just clean it and use a new gasket, Do not clean the thread locking compound from the threads. On a new valve check that the distance from gasket surface and the tip of the pintle is not greater than 28 mm.

You might also check that the throttle butterflies are closing all the way. If someone has tried to adjust them to control idle then the IAC won't be able to do its job and you'll get all kinds of funny idle.

HTH

Is fuel pressure good?
 
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boosteds10

Finally Fixed
Re: Wont start, Started troubleshooting tonight

I replaced the IAC with a brand new one, did not pull or push on the pintle at all. It does not even want to start now so there is no way for me to check things at idle.

As far as fuel pressure goes I dont have a gauge but Im gonna see if someone can bring me one.
 
sly dvl

sly dvl

Ya, it's got a Turbo
Re: Wont start, Started troubleshooting tonight

It was stated before but, have you checked your fuel pressure?
 
B

boosteds10

Finally Fixed
Re: Wont start, Started troubleshooting tonight

Funny part, my garage door is broken (its one of those huge heavy two wide woden doors), I pulled the ty in yesterday and opened it this mornin with the help of a friend of mine. he left and I dont have a gauge here, Id like to go pick one up but I have no way of getting the door down and noone is here.

I def need to check it because now it just cranks over and over, dosnt seem like its getting fuel.
 
SY2932

SY2932

Administrator
Re: Wont start, Started troubleshooting tonight

Here are my IAC scans from my service manual:





I would be swayed towards a bad ignition module at this point:

IMG_1831.sized.jpg

"If the chip is installed correctly, and you definitely have both spark and fuel pressure, your ignition module is dead. A bad ignition module won't generate a reference pulse preventing the injectors from firing. Part number is 1048-2827 (located under your distributor cap, BTW). Some auto chain stores can test to confirm if it's good or bad."

HTH's
 
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boosteds10

Finally Fixed
Re: Wont start, Started troubleshooting tonight

SY2932- I just read about that ignition module. Im gonna head out to the auto parts place at about 1:30 and pick up a FP gauge. Ill check to see if they have an ignition module in stock. If the FP is there ill go pick up that part.

Is this a part that just goes from working fine to dead instantly or no? Mine was intermittent for the last two hours but now it just wont fire at all.
 
JSM

JSM

Active member
Re: Wont start, Started troubleshooting tonight

Bad map sensor can cause this also.

If you had a scan tool you can verify a few things. Ignition modules seem to go bad often also but they usually just go bad and stop working. Let us know if you have spark.
 
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boosteds10

Finally Fixed
Re: Wont start, Started troubleshooting tonight

Ive got datamaster, my iac counts are a wierd number 167, the map is reading approx 100 with just the key on. Anything else I should look for?
 
Merk

Merk

Donating Member
Re: Wont start, Started troubleshooting tonight

Check ignition module
Check EGR valve (could be stuck)
Check for faulty ECM
 
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