Corsica misfiring after rain (nowadays problem with IAC valve)

Have a flashing light? Gauges acting funny? Bad idle? Get your problems solved...
User avatar
GT_Indy
Registered User
Posts: 512
Joined: Thu Apr 21, 2016 2:23 pm
Has thanked: 1 time
Been thanked: 6 times

Re: Corsica misfiring after rain

Postby GT_Indy » Mon Dec 04, 2017 7:05 pm

The alternator might need to come off for space.
The throttle body has 2 coolant lines but you can unbolt the TB from the plenum so you don't need to open the coolant lines.
Then vacuum lines and the throttle bracket and it comes off. Just be careful of the PCV hose under the plenum. It may be brittle and need replaced. Its a pre molded S bent hose you can find at local auto stores.
Other than that there isn't much to it. Vacuum lines run under and behind, gotta be careful not to crack those.

Yah its best to do it in warmer weather so stuff isnt brittle. Cold water and plastic will crack easily.

I don't recall a test lead but I know the pump can be run by removing the relay and jumping 12 volts to the pumps + wire. (Just dont send 12 volts to the grounds or ECM switch side.)

LOL Multifail. I like these Gen2 v6 engines. They always worked great for me. The Gen3 engines 3x00 series always gave me issues. But my 96 Beretta works great since I put a new engine and the new LIM gaskets. No more defects thankfully.


96 Beretta Z26 swap (Daily Driver).
90 Beretta GTZ (Summer Only Daily,124k Miles, Mesa, AZ Proving Grounds Vehicle).
90 Beretta Indy (Garage Queen, Registered as a Historical Vehicle, 17,365 Miles, 100% Factory, Yellow, Digital Dash, Sun Roof)

User avatar
Money pit Beretta
Registered User
Posts: 6384
Joined: Thu Jul 26, 2007 11:36 am
Location: Kansas
Has thanked: 2 times
Been thanked: 10 times

Re: Corsica misfiring after rain

Postby Money pit Beretta » Mon Dec 04, 2017 7:20 pm

The test lead is on the driver's side. Close to where the main wiring harness goes in the firewall. It's easy to find, looks like a connector with no home(no others near it).
Just throwing this out there: could the crank sensor have anything to do with the long starts?

For the old 3.1 it is best to turn the key on, let the pump prime and then start. That is also helpful when the pump is getting old and tired.

My 3.1 was a great engine. Started like a beast every time, but everything on the outside was new(just not the injectors) and the fuel pump was replaced.


keep'em flying!

User avatar
GT_Indy
Registered User
Posts: 512
Joined: Thu Apr 21, 2016 2:23 pm
Has thanked: 1 time
Been thanked: 6 times

Re: Corsica misfiring after rain

Postby GT_Indy » Mon Dec 04, 2017 7:30 pm

Oh. That connector. I always thought that was something else. lol


96 Beretta Z26 swap (Daily Driver).
90 Beretta GTZ (Summer Only Daily,124k Miles, Mesa, AZ Proving Grounds Vehicle).
90 Beretta Indy (Garage Queen, Registered as a Historical Vehicle, 17,365 Miles, 100% Factory, Yellow, Digital Dash, Sun Roof)

Bapsu
Registered User
Posts: 78
Joined: Mon Aug 14, 2017 4:05 pm
Has thanked: 2 times
Been thanked: 1 time

Re: Corsica misfiring after rain

Postby Bapsu » Tue Dec 05, 2017 9:42 pm

Money pit Beretta wrote:The test lead is on the driver's side. Close to where the main wiring harness goes in the firewall. It's easy to find, looks like a connector with no home(no others near it).
Just throwing this out there: could the crank sensor have anything to do with the long starts?

For the old 3.1 it is best to turn the key on, let the pump prime and then start. That is also helpful when the pump is getting old and tired.

My 3.1 was a great engine. Started like a beast every time, but everything on the outside was new(just not the injectors) and the fuel pump was replaced.
I dont think its crank sensor, since it always fires right up if I immidiately fire it up after shutdown. If I am waiting, I need o to crank. Weirdly not so much cranking with cold engine, though I was thinking that low / missing fuel pressure would cause even longer crank with cold engine.

Yeah I am always showing it few seconds power before trying to crank.

These engines are quite great. Also starting alwaysif just the ignition and fuel side are even somehow functioning (this one ran great with 4 cylinders when my ICM failed long time ago :D). Also cold starting at anywhere, last winter it was -25, no block heater. Took around one second cranking at the car fired up. Not much diference is it +20 or -20 lol.
GT_Indy wrote:The alternator might need to come off for space.
The throttle body has 2 coolant lines but you can unbolt the TB from the plenum so you don't need to open the coolant lines.
Then vacuum lines and the throttle bracket and it comes off. Just be careful of the PCV hose under the plenum. It may be brittle and need replaced. Its a pre molded S bent hose you can find at local auto stores.
Other than that there isn't much to it. Vacuum lines run under and behind, gotta be careful not to crack those.

Yah its best to do it in warmer weather so stuff isnt brittle. Cold water and plastic will crack easily.

I don't recall a test lead but I know the pump can be run by removing the relay and jumping 12 volts to the pumps + wire. (Just dont send 12 volts to the grounds or ECM switch side.)

LOL Multifail. I like these Gen2 v6 engines. They always worked great for me. The Gen3 engines 3x00 series always gave me issues. But my 96 Beretta works great since I put a new engine and the new LIM gaskets. No more defects thankfully.
Sounds like one weekend operation to take intake open and replace fpr... since its first time for me I am doing anything engine related than breather system repairs.

Haha I heard someone calling it multifail. Ur right, the engine itself is great and has no bad issues (specially the older generation). Also sounds good and has decent amount of torque to move these cars.



User avatar
Money pit Beretta
Registered User
Posts: 6384
Joined: Thu Jul 26, 2007 11:36 am
Location: Kansas
Has thanked: 2 times
Been thanked: 10 times

Re: Corsica misfiring after rain

Postby Money pit Beretta » Wed Dec 06, 2017 7:27 pm

The crank sensor was just a thought. Oh man the torque that they have is nice, sure miss that low end power now that I have the 3100. Did you locate the test lead?


keep'em flying!

User avatar
GT_Indy
Registered User
Posts: 512
Joined: Thu Apr 21, 2016 2:23 pm
Has thanked: 1 time
Been thanked: 6 times

Re: Corsica misfiring after rain

Postby GT_Indy » Wed Dec 06, 2017 7:38 pm

Money pit Beretta wrote:The crank sensor was just a thought. Oh man the torque that they have is nice, sure miss that low end power now that I have the 3100. Did you locate the test lead?


Yah these 3.1 engines always like they have better response than the 3100 version. The Gen3 should have higher up and torque though. Maybe they have torque management programmed in the ecm to reduce the low end pull?
Maybe its gearing too. The 3T40 I think is geared better than the 4T60e transmissions were.


96 Beretta Z26 swap (Daily Driver).
90 Beretta GTZ (Summer Only Daily,124k Miles, Mesa, AZ Proving Grounds Vehicle).
90 Beretta Indy (Garage Queen, Registered as a Historical Vehicle, 17,365 Miles, 100% Factory, Yellow, Digital Dash, Sun Roof)

Bapsu
Registered User
Posts: 78
Joined: Mon Aug 14, 2017 4:05 pm
Has thanked: 2 times
Been thanked: 1 time

Re: Corsica misfiring after rain

Postby Bapsu » Wed Dec 06, 2017 11:52 pm

Money pit Beretta wrote:The crank sensor was just a thought. Oh man the torque that they have is nice, sure miss that low end power now that I have the 3100. Did you locate the test lead?

GT_Indy wrote:
Money pit Beretta wrote:The crank sensor was just a thought. Oh man the torque that they have is nice, sure miss that low end power now that I have the 3100. Did you locate the test lead?
Didnt take look for it yet. Yeah, despite only 140hp power the engine is awesome with its torque. Also the th-125 is really cool combination with 3.1.

Yah these 3.1 engines always like they have better response than the 3100 version. The Gen3 should have higher up and torque though. Maybe they have torque management programmed in the ecm to reduce the low end pull?
Maybe its gearing too. The 3T40 I think is geared better than the 4T60e transmissions were.
Yeah I never had any car with gm 3xxx engine. American cars in this country are quite common but its more up to vans / fullsizes you see on streets. Corsicas / berettas / buicks and pontiacs alternative models with same engines are all really rare here. Seen once Saratoga. Beretta zero times ( have seen in sell). Few Corsicas, and some pontiac models. Maybe Chevy Van is the most common old school U.S car you see here.

Its too much german cars in this country... lol.



User avatar
Money pit Beretta
Registered User
Posts: 6384
Joined: Thu Jul 26, 2007 11:36 am
Location: Kansas
Has thanked: 2 times
Been thanked: 10 times

Re: Corsica misfiring after rain

Postby Money pit Beretta » Wed Dec 13, 2017 7:19 pm

It's getting just as bad around here, well for Beretta's that is. Lucky to see just one other on the road. Still see a Corsica or two.
So you are waiting for better weather to make anymore repairs? That is going to be a long wait.


keep'em flying!

User avatar
GT_Indy
Registered User
Posts: 512
Joined: Thu Apr 21, 2016 2:23 pm
Has thanked: 1 time
Been thanked: 6 times

Re: Corsica misfiring after rain

Postby GT_Indy » Wed Dec 13, 2017 7:38 pm

I agree it's too cold to be working on cars in this weather. Need a heated garage.

I'm interested to know how the leak is. I know a water leak in this weather causes the floor to become blocks of ice in these cars.


96 Beretta Z26 swap (Daily Driver).
90 Beretta GTZ (Summer Only Daily,124k Miles, Mesa, AZ Proving Grounds Vehicle).
90 Beretta Indy (Garage Queen, Registered as a Historical Vehicle, 17,365 Miles, 100% Factory, Yellow, Digital Dash, Sun Roof)

Bapsu
Registered User
Posts: 78
Joined: Mon Aug 14, 2017 4:05 pm
Has thanked: 2 times
Been thanked: 1 time

Re: Corsica misfiring after rain

Postby Bapsu » Wed Dec 13, 2017 10:24 pm

GT_Indy wrote:I agree it's too cold to be working on cars in this weather. Need a heated garage.

I'm interested to know how the leak is. I know a water leak in this weather causes the floor to become blocks of ice in these cars.
Money pit Beretta wrote:It's getting just as bad around here, well for Beretta's that is. Lucky to see just one other on the road. Still see a Corsica or two.
So you are waiting for better weather to make anymore repairs? That is going to be a long wait.
Haha yeah, had to rent my friends garage to finish the painting.

When I bought my own Corsica from my friend he told in the winter (when he drove it) he had like 5cm water on the floorpans, it was also freezing. It was cool to drive it and try to see something when windows got moisture on them if you drove shorter distances. Well, he has garage so it wasnt that bad problem.

My Corsica has most of leaks fixed for now. Passenger side seem to keep and drivers side has been good also since I added some sealant around the wiring harness on drivers side. Still needs to be done tho.

Money pit Beretta wrote:It's getting just as bad around here, well for Beretta's that is. Lucky to see just one other on the road. Still see a Corsica or two.
So you are waiting for better weather to make anymore repairs? That is going to be a long wait.
Yeah, its winter here for now. Nowadays winter here is around zero and sometimes snow, mostly water raining... sucks.

Gonna wait till spring until I do front brakes and oil pressure sensor again (arrrgh this time it better stay there in one piece) and then drive over summer of course. Maybe in August I could start taking intake apart and check for pressures and leaks, since its only the start nowadays, runs great fortunately.

Hows the winter at kansas? Snowing? If its snowing im jealous... Everyone says its damn cold in Finland. :D



Bapsu
Registered User
Posts: 78
Joined: Mon Aug 14, 2017 4:05 pm
Has thanked: 2 times
Been thanked: 1 time

Re: Corsica misfiring after rain

Postby Bapsu » Sat Jan 20, 2018 6:45 pm

Starting to suspect my injectors. There is always pressure (=starts well, havent measured pressure) on cold start, which basically rules out fpr. I think im gonna take upper intake apart soon. To test if injectors leak, can i just raise fuel line with injectors from engine and put power on to check if some injectors leak. etc?

Seems that less hard starts while its colder now (-10). I am also experiencing a bit erratic idle, nothing you see from gauge, but I can feel it with my ass that engine is stuttering slightly. Also idle with D engaged its quite low (around 600rpm). I guess injector would cause these idling issues also? Iac is functioning properly.



Bapsu
Registered User
Posts: 78
Joined: Mon Aug 14, 2017 4:05 pm
Has thanked: 2 times
Been thanked: 1 time

Re: Corsica misfiring after rain

Postby Bapsu » Mon Jan 29, 2018 9:54 pm

Yeah took the upper intake apart today. No big deal, took like 2 hours while doing it carefully (first time for me with this engine). Didnt have to touch alternator. Took out EGR, tbi body and cable bracket, map and air intake box of course. Already removed four bolts holding the rail, and also removed the bracket which is holding fuel lines in place. Rised up the whole fuel rail with injectors, but since it was snowing at the same time I decided not to start more investigation (I guess snow in cylinder isnt good thing...).

I need to catch up my friend for him to put power on while i take look whats leaking, right? How obvious is it looking if injector leaks? I mean is it one drip or like one spoon on fuel coming out when it shouldnt?



User avatar
ifixalot
Registered User
Posts: 576
Joined: Tue Dec 26, 2006 10:56 am
Location: Deerfield Illinois
Been thanked: 13 times

Re: Corsica misfiring after rain

Postby ifixalot » Tue Jan 30, 2018 1:05 pm

I've never witnessed a leaky injector but I'd assume you'd be able to see it. You could put paper towels under the injectors and if it gets wet, you know it's leaking. Do an ohm test on each injector too. They should be 11-12 ohms. You can pickup a cheap ohm meter at Harbor Frieght.
If an injector has low ohms, it's not injecting the proper amount of fuel and the ecm will compensate by enriching the others and those will be too rich. In addition, you should take out the plugs and look at them. Any abnormalities will point you to what is going on.



Bapsu
Registered User
Posts: 78
Joined: Mon Aug 14, 2017 4:05 pm
Has thanked: 2 times
Been thanked: 1 time

Re: Corsica misfiring after rain

Postby Bapsu » Sun Feb 04, 2018 9:01 pm

Yeah, lets see. I think I am also gonna fire up each injector straightly from battery to see how they spread fuel and do they leak after spray has ended...



User avatar
ifixalot
Registered User
Posts: 576
Joined: Tue Dec 26, 2006 10:56 am
Location: Deerfield Illinois
Been thanked: 13 times

Re: Corsica misfiring after rain

Postby ifixalot » Mon Feb 05, 2018 4:30 pm

I think the injectors run off 5 volts. Putting battery voltage to them might burn them out.




Return to “Diagnostic Help”

Who is online

Users browsing this forum: No registered users and 3 guests