no start after new opti
01-27-2006, 05:02 PM
#16
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Join Date: Dec 2004
Posts: 145
Re: no start after new opti
I'm telling you the MAF is bad, I bet if you unplug it, it will run. When this first happen to me when i put my brand new opti on, I thought it was the opti, I checked all the wires disconnected them reconnected them, and the same thing happen, I was told by a friend before I tear back into it to check the MAF, unplug it and try to start the car, it did not start on the first try but after a few it started fine, had it running for about 10-15 min, then to check to make sure the MAF was bad, I plugged it in when the car was running, it shut the car off right away. I'll bet it is the MAF.
01-27-2006, 09:28 PM
#18
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Location: elbert ,colorado, USA
Posts: 166
Re: no start after new opti
Sorry guys i am real buzy working, but tommaro i will try unplugging the MAF and see what happens . I am almost posibtive that i had the opti in the right spot (dowl pin) but i might have made a mistake who knows . Thanks alot guys for the replies i will keep u posted
01-28-2006, 06:54 PM
#19
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Location: elbert ,colorado, USA
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Re: no start after new opti
Ok tried the unplugging the MAF and nothing different, took opti back off and maid sure it it was aligned properly. took out some spark plugs and no spark, but the coil has power , and icm has power so once again stumped. is there any more places to check for power? Im about ready to blow this motor up .
01-28-2006, 07:38 PM
#20
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Location: Stillwater, OK
Posts: 308
Re: no start after new opti
Was the car running fine before the installed parts? If so, it must be either the ICM or the Coil. Having power doesn't necessarily mean it runs right. Pretty hard to install the opti wrong if it's the vented type. The non vented type is a bit tricky. Just finished installing the opti (original AC Delco) on mine and now there's no hesitation at 2500 rpms anymore.
01-29-2006, 04:55 PM
#21
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Location: elbert ,colorado, USA
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Re: no start after new opti
Its a new brand new ICM, but coil is about 4 months old, and i tried putting in my stock coil that i think is good and still no fire, i also put in my old computer and still nothing . How long is the warranty on the GM opti , i now have 2 brand new optis that im not sure if they are good or not.
01-29-2006, 06:48 PM
#22
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Posts: 145
Re: no start after new opti
try to start the car a few more times with the MAF off, remember it did not start the first time I tryed with it off, but it took about 10-15 times after that and it started everytime with it off after that.
01-31-2006, 10:22 AM
#24
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Re: no start after new opti
We have to assume you had the problem before you installed the new opti since you didn't answer the question but you had posted this:
You said:
You installed a new opti, ICM and coil.
You checked power at the coil and the ICM.
You checked for spark at a few plugs and found none.
Now for some questions.
You checked for power to the coil and the ICM but did you check for an effective ground at the ICM? See below
Did you check for spark at the coil?
Did you check for the presence of the IC signal at the white wire on the ICM?
Did you check for cam timing which subsequently effects ignition timing while you were removing the opti?
Did you check for the presence of 12 volts and ground going to the opti?
Did you check for the (2) 5 volt feedback signals from the opti?
If let's say you checked power at the ICM from the pink wire to the engine. It's possible the ICM has power going to it but not ground. When you checked the power wire and possibly put the other probe of the meter to a good engine ground it looked good. But, the ICM may not have ground going to it. Therefore, it won't fire the coil. When a device has power AND ground going to it, it's important to check power not to an engine ground but rather to the wired ground.
All of these items are simple to check, all you have to do is ask.
Originally Posted by ericz28w
well as luck would have it, new opti goes in , and no start. Still the exact symptoms burping out intake, blows out smoke sometimes.
You installed a new opti, ICM and coil.
You checked power at the coil and the ICM.
You checked for spark at a few plugs and found none.
Now for some questions.
You checked for power to the coil and the ICM but did you check for an effective ground at the ICM? See below
Did you check for spark at the coil?
Did you check for the presence of the IC signal at the white wire on the ICM?
Did you check for cam timing which subsequently effects ignition timing while you were removing the opti?
Did you check for the presence of 12 volts and ground going to the opti?
Did you check for the (2) 5 volt feedback signals from the opti?
If let's say you checked power at the ICM from the pink wire to the engine. It's possible the ICM has power going to it but not ground. When you checked the power wire and possibly put the other probe of the meter to a good engine ground it looked good. But, the ICM may not have ground going to it. Therefore, it won't fire the coil. When a device has power AND ground going to it, it's important to check power not to an engine ground but rather to the wired ground.
All of these items are simple to check, all you have to do is ask.
01-31-2006, 10:37 AM
#25
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Join Date: Oct 2001
Location: newton, kansas, USA
Posts: 6,070
Re: no start after new opti
Was the problem there before the new opti's and parts? if wasn't there then it has to be plug wires or opti. You have a timing issue if you are firing out the intake, and its most likely caused by your plug wires crossed or your opti one hole off.
01-31-2006, 06:02 PM
#26
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Location: elbert ,colorado, USA
Posts: 166
Re: no start after new opti
Thanks a bunch speedygonzales, i am very inexperianced when it comes to tech or elcetrical problems. I am gunna go down your checklist and see what i can find , i have a few questions but i will save them for last on the checklist, and ask later .
And the cars only problem before it died was that it would sputter at low rpms and act like it lost a lil power, but when prms got higher it would mellow out( i only drove it for a day with these symptoms so that is about all i remember) when car died it cranked and cranked with out the backfireing and burping. It only started backfireing and burping when i put in the new optis. I have taken the optis on and off about 5 times and everytime it is the same symptom
And the cars only problem before it died was that it would sputter at low rpms and act like it lost a lil power, but when prms got higher it would mellow out( i only drove it for a day with these symptoms so that is about all i remember) when car died it cranked and cranked with out the backfireing and burping. It only started backfireing and burping when i put in the new optis. I have taken the optis on and off about 5 times and everytime it is the same symptom
Last edited by ericz28w; 01-31-2006 at 06:13 PM.
01-31-2006, 06:10 PM
#27
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Location: elbert ,colorado, USA
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Re: no start after new opti
Ok for the questions on your checklist that iam un sure of how to do
"Did you check for cam timing which subsequently effects ignition timing while you were removing the opti? "
"Did you check for spark at the coil?"
"Did you check for the presence of the IC signal at the white wire on the ICM?"
Sorry for the inconvience of all the questions i am young and im learning as i go
"Did you check for cam timing which subsequently effects ignition timing while you were removing the opti? "
"Did you check for spark at the coil?"
"Did you check for the presence of the IC signal at the white wire on the ICM?"
Sorry for the inconvience of all the questions i am young and im learning as i go
01-31-2006, 06:19 PM
#28
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Location: newton, kansas, USA
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Re: no start after new opti
Originally Posted by ericz28w
Ok for the questions on your checklist that iam un sure of how to do
"Did you check for cam timing which subsequently effects ignition timing while you were removing the opti? "
"Did you check for spark at the coil?"
"Did you check for the presence of the IC signal at the white wire on the ICM?"
Sorry for the inconvience of all the questions i am young and im learning as i go
"Did you check for cam timing which subsequently effects ignition timing while you were removing the opti? "
"Did you check for spark at the coil?"
"Did you check for the presence of the IC signal at the white wire on the ICM?"
Sorry for the inconvience of all the questions i am young and im learning as i go
01-31-2006, 08:09 PM
#29
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Location: elbert ,colorado, USA
Posts: 166
Re: no start after new opti
Ok update, i think i tested the wires rite , i unplugged the connectors and tested there, correct me if im wrong. i used just a plain voltmeter,
ICM (key on)
pink-12v
yellow-ground
black-ground
green-nothing????
ICM ( cranking)
pink-6v
yellow-ground
black- ground
green- nothing again???
COIL , (key on) both wires have 12v
COIL ,(cranking) both wires have 12v
OPTI (key on)
purple- ground
blue-12v
green- (my meter only goes as low as 6) but was bouncing around at 6v
black- ('' '' " " " " " ") bouncing around 6v
OPTI (cranking)
purple-ground
blue- 12v to 6v
green- around 6v
black- around 6v
thak is all i found so far , so if any one could look at numbers and tell me whats wrong ,or if anything is wrong. It would be a huge help
ICM (key on)
pink-12v
yellow-ground
black-ground
green-nothing????
ICM ( cranking)
pink-6v
yellow-ground
black- ground
green- nothing again???
COIL , (key on) both wires have 12v
COIL ,(cranking) both wires have 12v
OPTI (key on)
purple- ground
blue-12v
green- (my meter only goes as low as 6) but was bouncing around at 6v
black- ('' '' " " " " " ") bouncing around 6v
OPTI (cranking)
purple-ground
blue- 12v to 6v
green- around 6v
black- around 6v
thak is all i found so far , so if any one could look at numbers and tell me whats wrong ,or if anything is wrong. It would be a huge help
Last edited by ericz28w; 01-31-2006 at 08:29 PM.
02-01-2006, 05:35 AM
#30
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Posts: 0
Re: no start after new opti
If you DISCONNECTED the plugs when you measured the voltages, then you have a problem. The first problem I see is the voltage on the ICM when you are cranking is 6 volts. If that voltage gets below I think about 9 volts, it won't work. Make damn sure the voltage is not 12 volts before you go any further. Measure it disconnected and connected. If you still have a problem proceed as written below.
First of all, if the voltage on the pink wire to the ICM is 12 volts when it is disconnected but drops to 6 when it is connected, the ICM is shot. If not, with the key off, disconnect the pink wire from the ICM and the coil. Now pull the 10A #11 fuse under the hood for the ignition. Now if you measure for DC voltage at both of those pink wires, it should read 0 volts from that wire to the black wire also going to the ICM. If it's not near 0, there is a problem. Now measure the resistance from the ICM pink wire to the pink wire going to the coil with the meter set to the low ohms scale. It should read 0 ohms. I suspect you have a problem with this connection some where from the point these 2 wires are spliced together.
Those 2 wires are connected together at a splice labeled S107. This splice is (according to the shop manual) about 6cm from where injector #3 wires break out of the main harness. Get back to us on what you find.
The next thing is what you call the yellow wire to the ICM. I think it's white but because of discoloration, it appears to be yellow. In any case, it is NOT ground. The black wire to the ICM should be ground.
The white or Yellow wire comes from the PCM and this is the IC signal you should measure with the meter set to AC. Check it to engine ground for a signal of 1 to 4 volts AC only when the engine is cranking. And NOT DC. It will not show up on the DC scale. If this signal is present, more than likely your entire problem revolves around the drop in voltage going to the ICM.
First of all, if the voltage on the pink wire to the ICM is 12 volts when it is disconnected but drops to 6 when it is connected, the ICM is shot. If not, with the key off, disconnect the pink wire from the ICM and the coil. Now pull the 10A #11 fuse under the hood for the ignition. Now if you measure for DC voltage at both of those pink wires, it should read 0 volts from that wire to the black wire also going to the ICM. If it's not near 0, there is a problem. Now measure the resistance from the ICM pink wire to the pink wire going to the coil with the meter set to the low ohms scale. It should read 0 ohms. I suspect you have a problem with this connection some where from the point these 2 wires are spliced together.
Those 2 wires are connected together at a splice labeled S107. This splice is (according to the shop manual) about 6cm from where injector #3 wires break out of the main harness. Get back to us on what you find.
The next thing is what you call the yellow wire to the ICM. I think it's white but because of discoloration, it appears to be yellow. In any case, it is NOT ground. The black wire to the ICM should be ground.
The white or Yellow wire comes from the PCM and this is the IC signal you should measure with the meter set to AC. Check it to engine ground for a signal of 1 to 4 volts AC only when the engine is cranking. And NOT DC. It will not show up on the DC scale. If this signal is present, more than likely your entire problem revolves around the drop in voltage going to the ICM.
Last edited by Guest47904; 02-01-2006 at 05:50 AM.