Corsica misfiring after rain (nowadays problem with IAC valve)

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GT_Indy
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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby GT_Indy » Sun Aug 26, 2018 7:03 pm

Bapsu wrote:Yeah took the dash out today.In case someones heading to same operation:

One nut at both sides, other near glove box and the other near fuse panel. Four screws just near windshield wheres the blower grill. Two nuts inside dash.

Things to be taken away;
Radio
AC-panel
Steering wheel, unbolt if from the dash and open the clamp holding it on the steering rack near firewall.
Take out cluster aswell. wiper controls and headlight switch also.

After removing those, unbolt and unhook the wiring harness going behind the dash. You really cant see much there, you just gotta feel it by hand where are the nuts and holders. Take all wirings out of the dash, disconnect heating hoses going to side vents. Pull dash out.

Not rocket science, did it myself first time on this car, took around 4hrs. Also, no need to deal with heater core!


That is good that the heater core didn't need to be pulled for the job.
When I did it I was parting a 90 Indy so I pulled everything, but its been years since then so I didn't remember the details.


90 Beretta GTZ
90 Beretta Indy

Bapsu
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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Bapsu » Mon Sep 10, 2018 6:00 pm

Yeah... Autumn pushing up in these weeks. Seems like
my daily driver corsica has developed slight misfire again during few last weeks.

When idling i hear constant popping from tailpipe every now and then. No smell of gas tho. Its also really slight, idle feels bit erratic while sitting inside. While driving its pulling great.

Last time i did plugs and wires, i guess now its icm & coils time? How does air leak act in this engine?



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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Bapsu » Sun May 19, 2019 7:53 pm

Well its time for inspection since summer is coming in...but:

Rear brakes failed. Last succeeded inspection i had 1.0kn (kilo-newtons we use here to measure brake power) on both rear brakes (drum ones). Now, I went to inspection and it failed coz rear brake power on both sides was only 0.6kn. With brake fully applied car running, i can rotate rear wheel by hand. Handbrake got 1.5kn power on both sides so thats ok. Here comes the intresting point: BOTH sides power has decreased (from 1.0kn to 0.6kn) significantly since last passed inspection.

Everything is basically new; cylinders, shoes and springs. Brake system also bleeded properly and brakes adjusted properly. No leaks found so far. What next?

I am starting to feel I got problem with the brake pressure? Front brakes are just ok and theres good power. Does master cylinder have some kind of pressure control valve which now limits rear brake pressure too much? Might whole master cylinder assembly be leaking internally and not generating enough pressure to rear brakes?

I dont think heres anything wrong with the lines itself, if lines was stuck, i would have problems on the stuck line side only??

Please help... this is driving me nuts soon.



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Rettax3
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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Rettax3 » Sun May 19, 2019 11:01 pm

Certainly sounds like a bad master cylinder or air in the lines. If you are sure there is no air in the lines, then consider replacing the master cylinder. Sometimes, an old cylinder will fail because the seals have pushed past the wear point it made under use when bleeding the system out -I've seen it happen a few times.


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26

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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Bapsu » Tue May 21, 2019 7:20 pm

Rettax3 wrote:Certainly sounds like a bad master cylinder or air in the lines. If you are sure there is no air in the lines, then consider replacing the master cylinder. Sometimes, an old cylinder will fail because the seals have pushed past the wear point it made under use when bleeding the system out -I've seen it happen a few times.
Yeah, indeed im starting to think about master cylinder.

One thing im not certain of; since master cyl has 4 lines going from it to each wheel, which brake circuit beretta/corsica has? I mean is it that rear wheels are one circuit and other one is front wheel, or is it "X-style", where front right and rear left are in same circuit and vice versa?

Asking that because if this car has X-circuit, then I should have problems at the front end too...



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Rettax3
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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Rettax3 » Tue May 21, 2019 11:27 pm

I was thinking about that too -I also thought L-Bodies used the 'X' configuration, but with your symptoms, I was second-guessing myself on that, and wondering if the export versions were built differently from domestic-market models. The cylinders on non-ABS cars simply use a front-half and rear-half dual-piston assembly, so you can trace your lines to verify.


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26

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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Bapsu » Thu May 23, 2019 9:40 pm

Rettax3 wrote:I was thinking about that too -I also thought L-Bodies used the 'X' configuration, but with your symptoms, I was second-guessing myself on that, and wondering if the export versions were built differently from domestic-market models. The cylinders on non-ABS cars simply use a front-half and rear-half dual-piston assembly, so you can trace your lines to verify.
Well, I got abs. And theres four lines going from the master to the wheels...

Anyway, got no much choices except master cylinder... all other parts are new..



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Rettax3
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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Rettax3 » Fri May 24, 2019 12:54 am

Hmm, that's right, your Corsy is a '93, I was thinking it was older for some reason, sorry. With the ABS-equipped cars, it is also possible that the ABS solenoids themselves are failing. Seems unlikely for BOTH rears to fail equally withing the same year though. Still thinking MC.


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26

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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Bapsu » Tue May 28, 2019 7:30 pm

Rettax3 wrote:Hmm, that's right, your Corsy is a '93, I was thinking it was older for some reason, sorry. With the ABS-equipped cars, it is also possible that the ABS solenoids themselves are failing. Seems unlikely for BOTH rears to fail equally withing the same year though. Still thinking MC.
Gotcha. I was the mc I guess. Installed used one from my donor car today, took even 10mins :lol: .

Bled the master cylinder, got most of the air out until ran out of brake fluid lol. Gotta keep bleeding more tomorrow, there was still some air on the mc and didnt even try to bleed wheels yet.

However, made the test; jacked car up and momma pressed brake pedal. Wheel didnt turn anywhere anymore, so theres now a lot more power than before on rear brakes.

Soon to inspection...



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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Bapsu » Tue Jun 04, 2019 4:59 pm

Well, bleeding doesnt seem to be that simple...

Have bled now for hours, first rearward mc screw, then foward one. After those each wheel. Dont seem to have much air on wheels, but mc bleed screws i keep having air no matter i do. Also brakes feel little soft and at least rear brakes i could turn by hand again....



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Rettax3
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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Rettax3 » Wed Jun 05, 2019 12:20 am

Did you bench-bleed the new MC before installing? Not bench-bleeding usually causes nothing but trouble throughout the rest of the process, like you described. Also, when bleeding at the wheels, do the farthest one first (right rear), then the next farthest (left rear), etc, ending at driver's side front. When bleeding, also try letting off the pedal slowly, like taking 3-5 seconds to come up, that can help too. I tend to try not pushing all the way down towards the bottom, particularly if it is an old MC (or rebuilt) as they can have problems if they over-travel into areas without previous wear (most especially old ones, as they may have small deposits built-up there).


1989 SuperCharged 3800 Srs-II (First)Six-Speed GTU
1990 Turbo 3.4 5-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 5-Speed Indy GTi (Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 LA1/L82 4T60E Z-26
1995 3.4 DOHC Turbo 5-Speed Z-26

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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Bapsu » Wed Jun 12, 2019 7:05 pm

Rettax3 wrote:Did you bench-bleed the new MC before installing? Not bench-bleeding usually causes nothing but trouble throughout the rest of the process, like you described. Also, when bleeding at the wheels, do the farthest one first (right rear), then the next farthest (left rear), etc, ending at driver's side front. When bleeding, also try letting off the pedal slowly, like taking 3-5 seconds to come up, that can help too. I tend to try not pushing all the way down towards the bottom, particularly if it is an old MC (or rebuilt) as they can have problems if they over-travel into areas without previous wear (most especially old ones, as they may have small deposits built-up there).
No I didnt. MC was from parts car. Neither let the mc empty... reservoir was full all the time, but ofc there migt been air still.

I got enough for that car for a while, since bleeding didnt seem to result anything. I really need to get some motivation and then tackle this shitty problem again with better time and motivation :D. Driving my pontiac for now...

I guess i need to completely bleed the system and if that doesnt help, i dont know... maybe still would be wise to buy new mc, as you told about this wearing problem.

Not like this brake issue eats my resources, but the car has some other problems too, in example lifters noise and gurgling from coolant system, gonna fix those too at the same time with the brakes...



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Re: Corsica misfiring after rain (nowadays problem with IAC valve)

Postby Bapsu » Wed Jul 03, 2019 7:54 pm

As interesting it gets, our another Corsica (also -93), identical to mine, has rear brake issues. It hasnt been inspected for a while neither, no idea what dyno would say about rear brakes. These ones I can aswell turn by hand while somoene applies brake. Wtf.

This one at least needs new front brakes and possibly might have some little leaks somewhere, so I will keep this updated. Focusing to get both of these inspected someday.




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