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Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: gdonovan] #1660357
09/06/14 05:59 PM
09/06/14 05:59 PM
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Raleighwood
2Bad360sfromNC Offline
top fuel
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Ah, cool! (other than I feel like an idiot lol) I just went and stuck the air hose on an extra WGA, and now I see. For some reason, I was thinking it was pulled open under vacuum. Manual boost controller operation makes sense now.


1968 Charger project. I don't have a fender tag or a buildsheet, so it's getting a 440. Help me decide on a color--most everything looks great! (NOT white. My Challenger is white. Need some variety :D)
1974 Challenger 360
2012 Challenger R/T
1991 Dakota 5.2
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: 2Bad360sfromNC] #1660358
09/06/14 07:49 PM
09/06/14 07:49 PM
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Irving, TX
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That's why I posted that pic on page 1.




Wastegates get some people a bit mixed up.


We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: feets] #1660359
09/08/14 08:59 PM
09/08/14 08:59 PM
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Castlegar, BC, Canada
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Allrighty! Latest News.

New fuel filter went in. Could still blow through old one, gas was nice and clean.

Put fuel pressure gauge back on rail, took car for a rip. Couldn't get more than 60psi on the fuel gauge when trying to boost, and also noticed that the bucking was occurring in relation to a drop in fuel pressure on the gauge.

Returned home, and tried to "deadhead" the pump by pinching off the return line. After pinching the line for 3-4 seconds, pressure started to climb steadily, but not by any means quickly. It reached about 70psi and called it quits. (And no, I didn't hold it there too long) and releasing the return line instantly returned the gauge to around 49-50psi at idle.

Weak pump?


Bloody Mary, Full of Vodka, Blessed art thou among cocktails....

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: That AMC Guy] #1660360
09/08/14 10:32 PM
09/08/14 10:32 PM
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Oakdale CT
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Quote:

Couldn't get more than 60psi on the fuel gauge when trying to boost, and also noticed that the bucking was occurring in relation to a drop in fuel pressure on the gauge.





How many pounds of boost were you running?

If 5 to 7 pounds the fuel pressure is correct. Close enough to be a non-issues I think.




"I think its got a hemi"
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: gdonovan] #1660361
09/08/14 10:57 PM
09/08/14 10:57 PM
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By the factory dash gauge, less than 5. More around the 2.5 - 3 psi range.... just tickling the turbo. I tried pushing the throttle for more boost and fuel pressure would not rise accordingly and was accompanied by more lurching.

A feller on the Turbo Dodge board gave me a bit of a formula for figuring out what pressure I need for boost over static pressure.

I need at least:
60 psi for 5psi Boost (which I'm barely getting)
66 psi for 10psi boost
71 psi for 15psi boost

He also said when I pinch off the return line I should also instantly see between 80 to 100 psi which I'm also not getting.


Bloody Mary, Full of Vodka, Blessed art thou among cocktails....

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: That AMC Guy] #1660362
09/09/14 01:20 AM
09/09/14 01:20 AM
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SD
Z
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Quote:

Weak pump?




Kinda what it sounds like to me.


It's Swifty! Swifty, you toad sucker!
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: zrxkawboy] #1660363
09/09/14 03:25 AM
09/09/14 03:25 AM
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Balt. Md
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From what I remember that system that had about 55 psi with the eng running and the vacum line hookede to the fuel press regulator. Pull the vacum line on the regulator and it would jump about 10 psi to about 65 and pinch the regulator return line line and instantly it would jump to about 100 and I mean right away. Seems to me even the non turbo systems like the V/6 mini vans that ran a system of about 38 to 48 psi would jump right to about 80 or more as soon as the return line was pinched. Thats about what I remember but its been years as Mopar went to the returnless EFI systems in the 90's on many systems. But if the press does not jump as soon as you pinch off the return line it sounds like the pump is weak. Is it weak enough to be your problem ?? Thats the question and as I said I have not worked on them for many years but it is more important for the reserve fuel pressure on the turbo cars. Ron

Last edited by 383man; 09/09/14 03:26 AM.
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: That AMC Guy] #1660364
09/09/14 07:27 AM
09/09/14 07:27 AM
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Oakdale CT
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Quote:



A feller on the Turbo Dodge board gave me a bit of a formula for figuring out what pressure I need for boost over static pressure.

I need at least:
60 psi for 5psi Boost (which I'm barely getting)
66 psi for 10psi boost
71 psi for 15psi boost





Nope its a 1:1 ratio.

0 boost = 55 psi
5 boost = 60 psi
10 boost = 65 psi

On the fuel pump- Early pumps would blow past 100 psi, later pumps and aftermarket top out at 70-85 psi.

You are having a low boost issue and the fuel pressure is fine, I think you are chasing a red herring at this point and you should focus on other areas.

A pound or two of fuel pressure will make no difference, these cars are not that sensitive to it.

I'd start with the basics- check your cam and distributor timing and go from there.




"I think its got a hemi"
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: gdonovan] #1660365
09/09/14 02:44 PM
09/09/14 02:44 PM
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Quote:

Quote:



A feller on the Turbo Dodge board gave me a bit of a formula for figuring out what pressure I need for boost over static pressure.

I need at least:
60 psi for 5psi Boost (which I'm barely getting)
66 psi for 10psi boost
71 psi for 15psi boost





Nope its a 1:1 ratio.

0 boost = 55 psi
5 boost = 60 psi
10 boost = 65 psi

On the fuel pump- Early pumps would blow past 100 psi, later pumps and aftermarket top out at 70-85 psi.

You are having a low boost issue and the fuel pressure is fine, I think you are chasing a red herring at this point and you should focus on other areas.

A pound or two of fuel pressure will make no difference, these cars are not that sensitive to it.

I'd start with the basics- check your cam and distributor timing and go from there.





I would agree a few pounds off on the fuel press does not sound like your problem. Just curious if you could wire the wastegate open and drive the car on just the eng to see how it runs. I did that years back to see how the car ran without any boost and to see if the problem was still there. Ron

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: 383man] #1660366
09/09/14 06:16 PM
09/09/14 06:16 PM
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Castlegar, BC, Canada
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The car runs perfectly fine as long as I don't get on the turbo. Only when I start boosting does the issue show up.

Cam and ignition timing has not changed. Has never been touched. Quite literally, this problem appeared overnight. Saturday the car drove fine, didn't touch it Sunday, and then Monday it was being difficult.

I've been following the how-to's on this webpage:

http://www.turbododge.com/forums/f4/f14/358339-checking-fuel-pressure-84-93-turbo.html

This is the part that worries me about the output of my fuel pump:

D)"Deadhead the Pump" by momentarily pinching off the return line, this will show you the pumps maximum output. Maximum output needs to be a minimum of 80 PSI and pressure needs to rise to max instantly.

When I dead-headed the fuel, it took several seconds for it to even climb to 70psi and that was as high as it would get. It was most definitely NOT instantaneous.


Bloody Mary, Full of Vodka, Blessed art thou among cocktails....

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: That AMC Guy] #1660367
09/09/14 08:49 PM
09/09/14 08:49 PM
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Quote:



Cam and ignition timing has not changed. Has never been touched. Quite literally, this problem appeared overnight.




These are all warning statements, I have fallen into the same trap.

All it takes is a pebble to get caught in the belt and jump it, been there and done it.

basics, basics, basics.

Feel free to chase the fuel pressure all you like, the pressure gauge indicates this is a non-issue.

If it makes you feel better replace the pump.

Its not going to fix the problem.

Quote:



Maximum output needs to be a minimum of 80 PSI




Only if you plan on running 25 psi of boost.





"I think its got a hemi"
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: gdonovan] #1660368
09/09/14 11:23 PM
09/09/14 11:23 PM
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Castlegar, BC, Canada
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Well, I'll double check them, but I'm nearing the end of my rope with this car. Nothing seems to help it.


Bloody Mary, Full of Vodka, Blessed art thou among cocktails....

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: That AMC Guy] #1660369
09/11/14 09:50 PM
09/11/14 09:50 PM
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UPDATE!

Back to basics. I do believe I found the smoking gun.

Dry Compression Test:

#1- 90 psi
#2- 130 psi
#3- 130 psi
#4- 130 psi

Plug #1 also has some silver speckling on the ground electrode. Methinks something may be askew in cylinder #1. Going to try a wet test to see what happens.

Wet Results:

#1- 100 psi
#2- 145 psi
#3- 135 psi
#4- 130 psi

Sounds like I've got a bad hole. The problem under boost must be a serious misfire.


Bloody Mary, Full of Vodka, Blessed art thou among cocktails....

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: That AMC Guy] #1660370
09/11/14 11:07 PM
09/11/14 11:07 PM
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Now for the really stupid part. I changed to a fresh set of Champion plugs (the RN12YC copper cores) and the car runs fine again!!!

That low compression in #1 still worries me, but it's not lurching under boost anymore!! I can't believe that. I never would've guessed it was a bad/fouled plug.

Thank you GDonovan for giving my head a shake. Back to basics for sure. I feel like such a jackass right now.

I'll probably just drive the wheels off the ol gal until that #1 hole becomes a real problem then giver the full-meal-deal rebuild. She's too nice of a car to just throw away.


Thanks for letting me pick your guys brains in for three pages! That's why I love moparts and have been an annoyance here for over a decade!!


Bloody Mary, Full of Vodka, Blessed art thou among cocktails....

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: That AMC Guy] #1660371
09/11/14 11:09 PM
09/11/14 11:09 PM
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Irving, TX
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Quote:


Thank you GDonovan for giving my head a shake.




Do we get bonus points for a swift kick in the rear?






Glad it's back together.


We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: feets] #1660372
09/11/14 11:22 PM
09/11/14 11:22 PM
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Grand Prairie,Texas
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I hope gapped the new plugs at .035. I found that to be best to keep the turbo from blowing out the spark. Yes it does happen. The wider the gap and the higher the boost the more it happens. PT cruiser turbos seem to suffer from that quite often.

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: feets] #1660373
09/12/14 12:02 AM
09/12/14 12:02 AM
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Quote:

Quote:


Thank you GDonovan for giving my head a shake.




Do we get bonus points for a swift kick in the rear?




Glad it's back together.




Everybody gets a big thumbs up and a thanks, you too Footses.


Bloody Mary, Full of Vodka, Blessed art thou among cocktails....

Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: That AMC Guy] #1660374
09/12/14 07:14 AM
09/12/14 07:14 AM
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Oakdale CT
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Quote:



Thank you GDonovan for giving my head a shake. Back to basics for sure.




No worries

It is very easy on these cars to slip into the mindset of "these as computer controlled fuel injected cars" and miss the forest from the trees, I have done it myself in the past several times.

It got to the point when I was doing anything drivability related to check the belt timing and a few other basics just to eliminate them as possible issues. About half the time (I kid you not) timing belt or distributor timing would be off.

Even though I have a full house here I still keep an eye out for the random k-car, they are all rotted away out here in the NE though and the Reliant won't be back together for another year or two.




"I think its got a hemi"
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: gdonovan] #1660375
09/12/14 11:04 AM
09/12/14 11:04 AM
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Irving, TX
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Quote:

Even though I have a full house here I still keep an eye out for the random k-car, they are all rotted away out here in the NE though and the Reliant won't be back together for another year or two.





If you hadn't wasted your resources with that whole marriage thing you could have done something important like work on the Reliant.



We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: '87 Shelby Daytona: Cutting Out/Bucking when Boosting [Re: Challenger 1] #1660376
09/12/14 11:18 AM
09/12/14 11:18 AM
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Cincinnati, Ohio
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Quote:

How's the spark plugs and wires,cap etc? They need to be in top shape for boost.




Spark plugs are always the first thing I change on a boosted motor when problem occurs like yours. When you said the were 10 months new I was thinking that's not fresh for a boosted motor.

The spark plugs in my alky dragster with 60 lbs of boost only last for 1 run for about 5 seconds under power.

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