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post #1 of 8 (permalink) Old 03-13-2010, 10:13 PM Thread Starter
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Hot start issues...

I'm hoping for someone on here that doesn't go to SCCoA may have a idea what's wrong with my SC..

Well my Hot start issue is still there, only needed to run the car for like 15-20 minutes, wait @ the same amount of time and it was hard to start and when it did it idle at like 400-500rpms very roughly and with like 1-2 inches of vacuum running EXTREMELY rich, with a mild smoke screen filling the back yard. It was running like that for nearly 5 minutes and it didn't change.. nor did the Check engine light even turn on?? You think idling at 400-500rpms, rich as sin would set off warning bells inside the ECU

Things replaced/tried:
  • Spark plugs
  • Spark plug wires
  • Fuel Filter
  • Positive Crankcase Ventilation Valve
  • Air Filter
  • Dis module
  • ECT sensor
  • Coil Pack (from a good running car with no issues at all)
  • Cam sensor
  • Crank Sensor
  • Idle Air controller (From TWO different cars that have no issues)
  • Throttle position Sensor (As above)
  • Injectors removed, `sonic cleaned', Checked for leaks, ectra
  • All Inter cooler tubing resealed twice
  • Inter cooler Replaced on second Tube resealing (had it sitting around, and i removed everything to make sure i had CLEAN surfaces)
  • Return Plenum checked
  • Grounds checked, and 4ga even added (Battery to chassis, Battery to Engine, Engine to chassis)

Only things not messed with/checked yet are:
  • Mass Air Flow sensor (does this same thing unplugged?)
  • Intake Air Temperature sensor
  • Barometric Air pressure sensor
  • Oxygen Sensors (how can it be them on start up?)

Now at this latest time, instead of blipping the throttle which always gets it to start to run `normally', i got out an Allen key and slowly opened up the Idle air bypass screw after like 2-3 turns out, it caught and started to run `normally' again.. after the car had a chance to clear itself with a few WOT throttle hits at the throttle body i shut it off, came back like 10 minutes later and it was easier to start (had a hint of not wanting to thou)

If any one can help me on this it would be awesome.

Previous threads on this same problems
Issue Link one
Link Two
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post #2 of 8 (permalink) Old 03-13-2010, 11:32 PM
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Quote:
Originally Posted by 91 XR7 View Post
[*]Mass Air Flow sensor (does this same thing unplugged?)
Usually when electronics fail, they work when cold... but when they warm up they fail. If you unplug your MAF and it doesn't change how the car runs... it usually means it's bad. Try replacing it with a known good MAF. Other than that, usually what causes those symptoms are a bad Crank sensor.. Did you replace the crank sensor or just test it?

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post #3 of 8 (permalink) Old 03-14-2010, 12:37 AM Thread Starter
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Well i always read that the ECU will go to a preset map for the MAF sensor (or any sensor for that matter) if it's unplugged.. and begin this car is 100% stock, down to Air silencer i think stock `back up values' should be correct..

Only spare MAF i have is the one in my '96 XR7 and the one in my '89 XR7 (i have the one in my '91 XR7, but i know THAT one won't work ) and i have a friend with a '92 SC i can beg to lend me his?

this issue has been getting worse and worse.. it was at the end of the summer 2 years ago (2008) it started doing this, but MINOR and only after really long drives (say 90-120 minutes?), Last summer it was getting annoying, i could drive it to work (seriously 5 minute drive) come out like 9 hours later and it would be hard to start... it needed like over night (12+ hours?) of sitting to start `normally'

Crank sensor was replaced, even thou the old one wasn't that old, but the Harmonic balancer was hitting it (well the ring at the back of it) Also the harmonic balancer was just replaced..
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post #4 of 8 (permalink) Old 03-14-2010, 11:35 AM
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thats a long laundry list

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post #5 of 8 (permalink) Old 03-14-2010, 01:06 PM
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the only thing i can think is the fpr, seems like the last link that or the ecu

if you want i can send you a chip tune that'll have her running better
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post #6 of 8 (permalink) Old 03-14-2010, 02:17 PM Thread Starter
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Originally Posted by crash00527 View Post
that's a long laundry list
And that list is only in the attempt to get it to run correctly (well other then the `normal' service items, since all my cars i give a full service when i buy them) But if i added in all the rest of stuff i've done to this car to get it to a level i like my cars to be at, the list would be a lot longer

Quote:
Originally Posted by decipha View Post
the only thing i can think is the fpr, seems like the last link that or the ecu
if you want i can send you a chip tune that'll have her running better
And like i've said on SCCoA the FPR is doing it thing with fuel pressures, it's not leaking back through the vacuum line either.. Hot or cold..



The car runs great other wise, heck if you shut off the car and restart it within say 10 minutes it usually restarts without a problem.. it's only after sitting fr alittle while (over 15 minutes?) and it'll have these issues..
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post #7 of 8 (permalink) Old 03-14-2010, 02:27 PM Thread Starter
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Here's my thing with this all..

Where i work, we build Cars with Flat four engines (Air cooled Volkswagen) ranging from 1600cc to 2332cc, all (all but the 1600) have 40 or 44MM Weber IDF carbs on them with a normal `electronic conversion' ignition system on them.. You can flood those engines (and anyone that knows webers know that's not hard to do) you can crank and crank, and as long as the spark plugs aren't fouled up it will start, and work it's way up to a normal idle (clear itself)

The only times that never happen is if the plug got fouled up (fuel closing the gap) or fuel was leaking down the throat..

I would think on a car with the ignition system of a SC should be able to able to clear a fouled plug? Also the fact that the EEC should be paying attention to the AFR that it'll do something to correct this problem.. even throwing a CEL or a Code in General, which it does not during this whole time..

So either the sensor not replaced (BAP, IAT, O2's, MAF) are giving the ECU wrong info, OR the ECU itself is screwed up
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post #8 of 8 (permalink) Old 04-04-2010, 11:09 AM Thread Starter
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Well this weekend it seemed to start better the 2 times i tried to start it, but i think just cleaning/checking all the connections and grounds was not the cure for the problem.

Also the idle seems pretty `lumpy' like it has a aftermarket Cam shaft in it.. once off idle (@1100rpm) it smooths out very nicely thou..

I hope i can get it sold thou.. too nice to tear apart
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