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electromechanics! help me!

S

stonecold0469

New member
A little info.
Its a swapped L67 Lumina
It has the following:
4" intake
Stage 2 zzp i/c
42# inyectors
Togs headers
3" exhaust
intense Stage 1 blower cam

So I took some time off work to do the i/c
I did. Car ran good. no wot runs considering no tune. Half throttle was fast, very resposive and strong.
After the second day. It started to go bad.

Symptoms
-car would go to 1500-2000 RPMs on its own.
-it would shift to 2nd after reaching 3800 RPMs.
-fuel gauge goes to full then back to empty.
-tried to go half throttle with a no go. Even full throttle doesnt run good. It feels like it loses voltaje.
-alternator went bad. Replaced it. Still does the same thing. Replaced it Sunday. Used the car only today and now its not charging again.

Codes:
P1635
P0300
P0118

Any help?
 


Did you use the Garleak gaskets that ZZP puts in their kits? If so..that's the best possibility. The Garleaks suck and cause vacuum leaks etc.

I've always made my own with a roll of gasket paper and added a little Permatex 26B around all areas I needed to be sealed. Never a leak.
 
is the battery ground loose or have corrosion on it? if not maybe its a bad battery.

P0300 could be from the cam, most of the cams will set that code and you just set it to "no reporting" with a tuner.
 
P1635 is a code for the 5V reference signal for many of your sensors; TPS, MAF, MAP, IAC. The code may be setting because the system voltage is dropping below the threshold which is about 11.5V.

Did you swap an entire wiring harness when you put the 3800 in the car?
 


Yes. The car has a 1998 LTZ harness with a 98 gtp pcm.
The aeroforce was reading throttle percentage and voltage. Now it doesnt.

Im looking for harness pins diagram. To verify 5 volts references and grounds with a multimeter.

I have not checked voltage to any other sensor.

As far as fuel gauge. I checked if with the signal I took for the water pump was the issue.
Installed a switch to the water pump. And still is not good.

I exchanged the alternator at AutoZone. The other one was good but they decided to give me another one.

Ill have to check for voltage at the harness pins if they are fine. My guess would be pcm.

But thats all ive got
 
stonecold0469 said:
-alternator went bad. Replaced it. Still does the same thing. Replaced it Sunday. Used the car only today and now its not charging again.
Click to expand...

I would fix this before checking reference voltages.

Would it run good if you put a freshly charged battery in the car?...Then start running bad when the battery wore down?
 
Have you unplugged the PCM to check that there are no bent pins and that the connectors are fully seated? How are checking the voltage?..with a DVM, gauge, or cluster?
 
Another thing you can do is disconnect the battery and check the resistance from the + battery cable to ground. It should be 100 kohms or higher.
 


Have you unplugged the PCM to check that there are no bent pins and that the connectors are fully seated? How are checking the voltage?..with a DVM, gauge, or cluster?

I unplugged it, it looked fine.
Aeroforce and multimeter.
 
I just read that my car needs almost 15 volts. And im getting 11 to 12. Apparently this is causing the hesitations I feel when I go half or wot. There is something wrong. Battery is in working order. It keeps a charge and stays at 12.3 -12.6 volts.

The problem im having must be all related.
Before saying its a bad pcm. I believe maybe if it is something in the harness.

Im gonna try tomorow the pins of the pcm connectors, verify thath they have +12 volts and -12 volts.
And also the 5 volt reference.

If I verify voltage at the alternator wire...would it give me an idea if its charging more?
And that the amperage is not reaching the battery?
 
Perform a voltage drop on the alternator wire. You shouldn't drop more than .5V across that wire. Put the red lead of your DMM on the alternator output post and the other lead on the battery positive post with a voltmeter set to DC voltage and the car running.
 
hitman92499 said:
Perform a voltage drop on the alternator wire. You shouldn't drop more than .5V across that wire. Put the red lead of your DMM on the alternator output post and the other lead on the battery positive post with a voltmeter set to DC voltage and the car running.
Click to expand...

According to what he said the battery is staying charged and that requires at least 13.5 volts at the battery from the alternator.

What I would do is start pulling relays and fuses until the system voltage comes back up to the 12-13 volts that is required. Another thing you can do is power the PCM from a remote source like a good battery. I use the 12 volt batteries that are in things like small air compressors that you buy at Walmart. These batteries are a really good source of DC voltage with absolutely no ripple.
 


The battery keeps 12.3-12.6 volts.

Sometimes voltage just drops bellow.
Whats a "ripple"?
And powering the pcm? To know if its not receiving enough voltage?

I dont want to open the harness yet.
 
Rico said:
According to what he said the battery is staying charged and that requires at least 13.5 volts at the battery from the alternator.

What I would do is start pulling relays and fuses until the system voltage comes back up to the 12-13 volts that is required. Another thing you can do is power the PCM from a remote source like a good battery. I use the 12 volt batteries that are in things like small air compressors that you buy at Walmart. These batteries are a really good source of DC voltage with absolutely no ripple.
Click to expand...

Just because the battery stays between 12.3-12.6V means nothing. You could accomplish this with a 14 gauge wire given the amount of current necessary to just run the vehicle. My worry is under electrical load situations, the wire simply cannot provide the current necessary to do. Plus, it's a 15 second test, so why rule it out?
 
The battery keeps 12.3-12.6 volts.

Sometimes voltage just drops bellow.
Whats a "ripple"?
And powering the pcm? To know if its not receiving enough voltage?

I dont want to open the harness yet.
 
Ripple is the AC voltage created by the alternator that does not get rectified to DC by the diodes. It is normal to see anything less than .5V AC at the battery at any given time. Anything over that means the diodes are not doing their job. Car can't run on AC.
 
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