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84 w/CF won't start

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c4ever

Guest
Ken,
I would correctly time the engine prior to doing anything else. The plug to disconnect should be fairly easy to find. Brown single wire just to the left(drivers side) of distributor. ( I may be wrong about the color but pretty sure it was brown)

Carlo
 

Twin_Turbo

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Messages
618
Location
Enschede, The Netherlands
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You can't set base timing w/ the HEI bypsass not disconnected. It's a brown or tan wire running from the distr. to the firewall. It has a connector in it to disconnect the thing.

With minimum air set too low it IS possible that the idle rpmis so low that the ECM can't compensate (IAC's fully open). Also, the ECM will try to position the IAC's around pos # 35-55 so if they are out of that range because of minimum air setting you will have a hunting idle.

Marck
 

vigman

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88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
The ECM is working

So... the single Brown wire is near the wiper motor/ master Vac booster. single connector like your O2 sensor.

It might be lost or spliced or something...since you car was caniblized... keep searching or we can make a NEW interuption point...

I'll check the book tonight on the electrical where's waldo.

While your down this far..... do the O2 & EGR
It will save you headaches later.

Again....just my opinion.



Vig!
 
Joined
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Messages
160
Location
Matthews, NC USA
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HEI bypsass

Here is how the distributor is currently wired.

Heavy Tan wire connect to Bat term. on cap
Tan wire connected to Tach. on dist. Cap
1 - Connector from dist. to dist. cap
1- connector from dist to another connector coming from firewall.

No single wire from dist. to firewall.

where is this wire connected on the distributor?

All TB vacuume ports capped
EGR valve capped
All unused vacuume lines capped.

Also, there is no MAP sensor

Ken
 

vigman

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Ohhhhh

Gotta have a MAP sensor.....

No codes???? The MAP is on the firewall square black plastic box with a 3 pin connector on bottom and 1 vac line going to manifold.


Will whip out book... brb

Vig!
 

vigman

Motor head!!!!
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88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Here we go

From the HEI distrib.

this connector exits out of the back of the distrib not part of the CAP.

There is a 4 pin connector
Pin A White to the ECM pin D4 ( EST )
Pin B Purple/White to ECM B5 ( REF )
Pin C ( THIS IS THE ONE )
Tan/Black... C-106 is the connector your looking for to ECM pin D5
Pin D Blk/Red GROUND from ECM Pin B3

This is the ECM inputs/output to control spark!

The ESCM ( electronic spark control module ) is a seperate deal and sends JUST the knock signal into the ECM on pin B7

These colors & pin numbers are for an 88
BUT the function is the same.. checking for an 84 now!


Vig!
 

vigman

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88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
The connector you seek

Should be hiding around the back of the rocker cover drivers side twds firewall.


The TAN/Black goes to pin 10
( smaller ECM connector ) of the ECM on an 84

MAP sensor
Pin A purple
Pin B Light Green
Pin C Gray

The way to find it ..unplug the 4 pin connector on the distrib.. and chase it thru the harness.


Vig!
 
Joined
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Messages
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Location
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1984 Coupe
MAP Sensor

Vigman,

Thanks for the info, I'll check it out ASAP.

I think I may have found the offending wire. There is a light colored wire with a shovel connector pulled out of the wiring harness that appears to go to the fire wall.


Would the lack of computer controlled spark cause the backfiring?

Still puzzled over this issue?

thanks for all the help,

Ken
 

vigman

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88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Hmmmm

It shouldn't be a SPADE style connector...

Unless........... they BROKE the factory one.

And since you don't know IF the circut is complete..you don't know if your in RUN mode
or set timing mode.

Clue here...IF the ECM is functional 100% the check engine light will come on IF that circut is open.

Suspect EVERYTHING!


Vig!
 

vigman

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88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
AND

The backfiring MIGHT be thru improper timing.

Vig!
 
Joined
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Messages
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Location
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Timing Set

I was at home this moring so I started the engine and once it was warm enough to idle, I disconnected the suspect wire.

The engine immediately reacted by slowing down even further. I set the timing to 6bdc as the radiator label indicated and reconnected the suspect wire.

The idle came up and the TPS seems to be working now. I can let off the throttle at any position and the engine returns to an idle.

The map sensor was there and intact but was missing the vacuume line. Replaced it and every is running, but still seems to be starved for air.

Got new IACs and will let you know how they worked.

Ken
 

vigman

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88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
NOW

Pull the power on the battery 1 min.........

Restore power.......

Start car and shut it down within 10 seconds.......

Restart........

Now the car should relearn everything.....


Vig!
 
Joined
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Messages
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Location
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IACs

Ok, relearning will be the next task.

Put in the new IACs, but the pintle didn't reach all the way to the hole. The instructions mentioned making it shorter but nothing about making it longer. I didn't want to do anything until I asked.

Got any suggestions?

You can definitly hear the vacuume leak, but seems to run ok.

I feel like I'm close....

One more missing sensor (EGR solenoid) to add and I'm done.

Looking forward to driving the vette for a while.

Thanks for the help,

Ken
 
S

Shadowing1985v

Guest
reason they stop puting cross fire in vettes

is cause it never sends equal amounts of fuel on both sides

ushould save some money up and change it over to tune port
 
S

Shadowing1985v

Guest
hmm

forgot to mention, as i was reading the posts

i was going to say maybe it is your cold start valve
i just put my engine back together today
and had the injector wire on the cold start valve and the cold start valve ont eh injector "same connectors"
and the car would just sit there and click

im not sure if 84's have cold start on them or not though
 

Twin_Turbo

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1982 Twin Turbocharged Red/Black
Well, that's really helpfull telling his engine sucks and he should've gone tpi....

I do a lot of crossfires and you can get them to runs silky smooth.

Crossfires don't have cold start valves...and it's called a cold start injector.

How can't it send equal amounts to both sides? it's a 360 degree manifold, okay it does have distribution problems but not side-side...more like 1 and 8 running leaner.

Okay, if the 1st TB sprays the fuel pressure at the 2nd one drops a bit, thats why they have staggered injectors.

Don't sweat about the iac pintle...go for a cruise and if you go above 35 mph the pintles should reset and extend all the way.

You're almost there :D
 
Joined
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Messages
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Location
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1984 Coupe
Drive over 35?

>ushould save some money up and change it over to tune port<
I just consider the source and let it go. There are some who subsitute opinions for knowledge.

AS far as the IAC's are concerned??

Do you have to drive at this speed for more that a few seconds?

I got it up to 40mph last night but only for a couple of seconds.

Ken
 

Twin_Turbo

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Messages
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1982 Twin Turbocharged Red/Black
It's an 84 ECM and it's slow, I'd drive it up to 50mph to be sure it resets the TB's. However, it HAS to be in closed loop and the ECM shoudl get the VSS signal. That the dash works doesn't mean the ECM gets the VSS signal. Do you have a scanner?

MArck
 

vigman

Motor head!!!!
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88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
IAC shutoff

40mph 2 min or so.

SO how's it run off idle?

Smooth?
Power good?


What's next?


And Shadow... SHUT UPPPPPPPPP!

Your TOTAL LACK of communicating anything of use in the ENGLISH language is a DISTRACTION.

X fire is an ok platform.

It's better than a carb ( in this application )

NOT EVERYONE WANTS 350 HP @ THE REAR WHEELS!

Better to be thought of as a fool then to remove all doubt by opening your MOUTH!


Vig!
 

vigman

Motor head!!!!
Joined
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Messages
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Location
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Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Ken

You bought FACTORY GM IAC's RIGHT?

Not the Standard Ignition type ADJUSTIBLE????!!!!!! ( Red Box )

The after market ones you can adjust the pintle the GM ones you can not!

The GM ones will be the correct ones.


Vig!
 

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