Hard Hot start Part 3

9

91 XR7

Registered User
Would the sparkplugs and/or Spark plug wires cause a hard to start issue only when hot?? even thou the wires look good and not burnt, but this issue started like 6-9 months after i did a full service on the car (Plus and wires, oils, filters, ect.) and i'm at a lost of what it could even remotely be now..
since been nearly 4 years now since i swaped in the engine on my '89 XR7, but can you RE&RE the lower IC tube without removing the drivers acessory bracket?? I may take everything off, take it to work, clean all sealing surfaces good, and then reseal everything again.

May just do the O2 sensors aswhile, but correct me if i'm wrong (Fraser, Dave) that the ECU doesn't pay attention to them at start up?? ) Are Denso or Bosch any good?

Thanks for any thoughts..

PS; If you don't know what my issues are with my '91 SC, search for `hot start issues' threads by me :)
and as too date:
Replaced: Cam, Crank, Ect, IAT, DIS, Sparkplugs and wires (before this issue started thou), Injectors
Swapped out: MAF, BAP, IAC x 2, Coil Pack and ECU
Moved : Dis module relocated in front of Radiator with huge heat sink
Cleaned: ALL grounds, Connectors
Added: 4ga Chassis to engine, Chassis to battery, Battery to Alternator
 
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91 XR7 said:
Would the sparkplugs and/or Spark plug wires cause a hard to start issue only when hot?? even thou the wires look good and not burnt, but this issue started like 6-9 months after i did a full service on the car (Plus and wires, oils, filters, ect.) and i'm at a lost of what it could even remotely be now..
since been nearly 4 years now since i swaped in the engine on my '89 XR7, but can you RE&RE the lower IC tube without removing the drivers acessory bracket?? I may take everything off, take it to work, clean all sealing surfaces good, and then reseal everything again.

May just do the O2 sensors aswhile, but correct me if i'm wrong (Fraser, Dave) that the ECU doesn't pay attention to them at start up?? ) Are Denso or Bosch any good?

Thanks for any thoughts..

PS; If you don't know what my issues are with my '91 SC, search for `hot start issues' threads by me :)
and as too date:
Replaced: Cam, Crank, Ect, IAT, DIS, Sparkplugs and wires (before this issue started thou), Injectors
Swaped out: MAF, BAP, Coil Pack and ECU
Moved : Dis module relocated infront of Radiator with huge heat sink
Cleaned: ALL grounds, Connectors
Added: 4ga Chassis to engine, Chassis to battery, Battery to Alternator
Click to expand...

O2 sensors do not switch until after the EEC has entered closed loop (Warm)...
 
91 XR7 said:
Would the sparkplugs and/or Spark plug wires cause a hard to start issue only when hot?? even thou the wires look good and not burnt, but this issue started like 6-9 months after i did a full service on the car (Plus and wires, oils, filters, ect.) and i'm at a lost of what it could even remotely be now..
since been nearly 4 years now since i swaped in the engine on my '89 XR7, but can you RE&RE the lower IC tube without removing the drivers acessory bracket?? I may take everything off, take it to work, clean all sealing surfaces good, and then reseal everything again.

May just do the O2 sensors aswhile, but correct me if i'm wrong (Fraser, Dave) that the ECU doesn't pay attention to them at start up?? ) Are Denso or Bosch any good?

Thanks for any thoughts..

PS; If you don't know what my issues are with my '91 SC, search for `hot start issues' threads by me :)
and as too date:
Replaced: Cam, Crank, Ect, IAT, DIS, Sparkplugs and wires (before this issue started thou), Injectors
Swaped out: MAF, BAP, Coil Pack and ECU
Moved : Dis module relocated infront of Radiator with huge heat sink
Cleaned: ALL grounds, Connectors
Added: 4ga Chassis to engine, Chassis to battery, Battery to Alternator
Click to expand...

Mine does this sometimes, it starts in that situation every time if I kick the pedal once while turning it over. I was thinking O2 sensors myself...
Not annoying enough for actioning IMO..
 
91 XR7 said:
Would the sparkplugs and/or Spark plug wires cause a hard to start issue only when hot?? even thou the wires look good and not burnt, but this issue started like 6-9 months after i did a full service on the car (Plus and wires, oils, filters, ect.) and i'm at a lost of what it could even remotely be now..
since been nearly 4 years now since i swaped in the engine on my '89 XR7, but can you RE&RE the lower IC tube without removing the drivers acessory bracket?? I may take everything off, take it to work, clean all sealing surfaces good, and then reseal everything again.

May just do the O2 sensors aswhile, but correct me if i'm wrong (Fraser, Dave) that the ECU doesn't pay attention to them at start up?? ) Are Denso or Bosch any good?

Thanks for any thoughts..

PS; If you don't know what my issues are with my '91 SC, search for `hot start issues' threads by me :)
and as too date:
Replaced: Cam, Crank, Ect, IAT, DIS, Sparkplugs and wires (before this issue started thou), Injectors
Swaped out: MAF, BAP, Coil Pack and ECU
Moved : Dis module relocated infront of Radiator with huge heat sink
Cleaned: ALL grounds, Connectors
Added: 4ga Chassis to engine, Chassis to battery, Battery to Alternator
Click to expand...

If it's acting like the engine is flooding and requires you to hold the throttle open on warm restarts, suggest you try resetting the adaptive strategy by disconnecting the battery for 5 minutes. It may also be the summer fuel formula that's causing the problem.

David
 
David Neibert said:
If it's acting like the engine is flooding and requires you to hold the throttle open on warm restarts, suggest you try resetting the adaptive strategy by disconnecting the battery for 5 minutes. It may also be the summer fuel formula that's causing the problem.
David
Click to expand...

The battery has been disconnected many times.. even during the ECU swap :p
Also when i get it to start and it idles @ 400rpms, w/ nearly no vacuum you can open up the idle air by-pass screw and it'll `catch' and rev up to @ 1800? rpm and slowly come back down.. as like any `normal' starts that car will have when cold or started soon after shutting it off..

Also the ECU that is in the car was unplugged (from the harness) for over 3 days so that has GOT to clear everything and anything :)
 
BirdofPrey97 said:
When I had this issue ended up replacing the EEC and then found the DIS to be bad as well. Car runs fine now.
Click to expand...

DIS module is new so.. with two different ECU's it does the same thing..

pablon2 said:
I see you mention you relocated the DIS, but did you swap it with a known good one as well?
Click to expand...

It's a used one, but doesn't matter which i used the new one that's bolted to the Accessory bracket or the known good one (that's from this car originally, and been on my '89 XR7)
 
Can you communicate with the computer using a scanner? Or, get codes out of it? Check your referance voltage, should be almost perfectly 5v. If it isn't the ECU is done. Back probe the computer and check all your grounds, and hots. Ford says the difference between battery ground, and hot should not be greater than 300mV. How many miles on car? If its a lot, have you tried another IAC? I see these go bad ALL the time it seems like. Borg Warner finally makes one that works good off the shelf if you hit up the local parts store.
 
HwyStar said:
Can you communicate with the computer using a scanner? Or, get codes out of it? Check your referance voltage, should be almost perfectly 5v. If it isn't the ECU is done. Back probe the computer and check all your grounds, and hots. How many miles on car? If its a lot, have you tried another IAC?
Click to expand...

That's the down side, I just got a generic code reader. But there is never a single Code thou.. i had it seriously run at @400rpms for over 5 minutes, came back out, opened the air-bypass bleed screw a few turns, and it caught, turn back the screw.. shut it off, checked for codes NOTHING!

Reference Voltage is good..
Return Signal (Sensor ground) is good.
Battery Voltage at MAF, injectors, IAC is good..
Grounds for MAF, O2's

I have tried 2 other Idle Air Controllers.. One spare i had, and one off my '91 XR7.. Also i have a IAC tester :eek:

The car itself has around 100,000miles on it

If i can get a 60 pin harness connector i may make my own `break out box'.. Shouldn't be THAT hard to make :eek:
 
Ok, you have to be sure about this, is the ECU giving you the 1, 1-2 flash when you hook you're generic code scanner to it? Meaning no codes present? Also, I would check the referance voltage at the Data Link Connector to ground. Black/White Stripe I think. That is one channel. And there is another reference voltage channel, can't think of what pin, or color right off hand, but would be best to check at ECU connector. There two reference voltage channels, and not kidding, if you see 5.10 or greater, the ECU is smoked. It sounds like a pain, but make sure the grounds and hots are good AT THE COMPUTER. There are several of each that run in to it. Make VERY sure that the shield wire that comes in from the DIS is grounded somewhere on the body near the computer. Thats the wire that doesn't have any insulation on it. At a point before it reaches the computer, it and another ground(which goes to the computer...) share a eyelet with a screw through it that breaks off a lot, and is a sure way to cook the ECU.
 
My code reader has a digital Display ;) i got this one because i knew i'll screw up on the beep/flash counting thing :eek:

All the following is from my '91 EVTM shop Manual, and Alldata Software too :

* Technically there is only one 5V output, and that's for the TPS and BAP sensors and that will be the Brown w/ White tracer coming from pin #26 of the ECU but doesn't go to the Self test/Data connector
* There's a circuit (359) which is called `Reference Voltage (Sig Rtn)' that's a Grey(gray) w/ Red tracer coming from pin # 46 of the ECU.. and it's a Ground for the Knock sensor, Clutch/neutral switch, O2 sensor, Octane plug, BAP, TPS, IAT, and ECT and also goes to the Self test/Data connector (to trigger the self test)
* The ignition Shield wire is good, and the one grounding point near the ECU, which is the same grounding point for the ground for pin # 20 at the ECU (Supposedly is the Case ground) and for reference, that shield wire is also grounded at the Crank sensor through on of the bolt holes..

Grounds:
Pin 20: as described above, is more/less Case ground (shield)
Pin 40, 60: Grounds from ECU circuitry (coming from the ground near the battery)
Pin 46: Ground output to BAP and TPS (Signal Return) connected inside ECU to pins 40 and 60
Pin 6 : Ground, related to the VSS input Via pin # 3 at ECU (Reference)

Sorry to sound like an ~~~ but.. i do have a schematic, and i know how to read / use them :eek: I still like to rip out the whole harness, but getting it out of the firewall seems abit fun (tried on a '92 SC at a dismantler)
 
Just making sure, most people don't have the diagram. The shield wire(I think) would pop the computer if not grounded. Only reason I said to read the flashes, or analog meter, is to make sure that the PCM is doing something when you ask it to, tells you that it does a little more than start up. But, you did check the ground for the shield wire? Its really easy, next to the ECU.
 
HwyStar said:
Just making sure, most people don't have the diagram. But, you did check the ground for the shield wire? Its really easy, next to the ECU.
Click to expand...

Oh'yah.. i have diagrams, and know how to use them :) Alot of people aren't to happy to do electrical work, and get confused when they see schematics but i enjoy doing wiring, electrical work.. and reading schematics is nothing for me. At work, i take OEM DBW VW engines, and swap them into the cars i build using all the OEM wiring, sensors, ect..
I usually get into this trance kinda state, where i have no idea what time it is, and if i'm listening to music (usually Ipod) i can't hear people talking to me :)

yes i did check those wires (Ignition shield wire, Case shield) cleaned the ring terminal, the body.
 
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