possible mechanical causes of erratic Idle?? fixed!

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possible mechanical causes of erratic Idle?? fixed!

Unread postby BongoBob » Thu Apr 09, 2015 10:59 am

Greetings all ! I've got my tune sorted out but the dang idle is giving me hives Assuming the tune is correct and it is because sometimes it will idle perfect at 900rpm. Here is quick description tps.85v**iac works or at least the tweecer says it is , I have a new el cheapo distributor installed , timing at 10b,fuel pressure 40psi.If you had to diagnose this problem where is the best place to start.? Sometimes its perfect sometimes it wants to stall and if I put it into park or neutral at the point before it stalls it will usually idle abot 1800 to 2k rpm
I know the throttle body leaks at the shaft is this an issue with speed density?? should I start there?
runs perfect except for that idle gremlin.
Ideas? advice? diagnostic procedure?? Any help will be greatly appreciated Thanks again Bongo Bob
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Vehicle Information: 93 Lightning Wrecked the last one This one stock as far as I can tell except for FRPP (powerdyne) blower kit and Pro-m/dunnerite mass air conversion. Has Banks tc200 trans controller 24lb injectors and a Ford Cobra 24lb mass air meter. Using unchipped a9l for engine control and stock c3p1 for the transmission wideband by innovate
Vehicle 2 Information: FFR Roadster 408w mas flo Tremec 5speed ,moser axles worked dart heads
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Re: possible mechanical causes of erratic Idle??

Unread postby red5.0fogger » Thu Apr 09, 2015 12:14 pm

On a SD car I would think leaky shaft could be acounted for by just a tad less throttle opening on the screw. Unmetered air is a none issue on SD since it calculates it rather than measure it.

Back when mine was SD I would be looking for other possible vac leaks or simply too far open on the idle screw. Can you try the base idle reset in the write ups?
If it doesn't like that procedure I would almost have to say its a vac leak.
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Re: possible mechanical causes of erratic Idle??

Unread postby decipha » Thu Apr 09, 2015 1:38 pm

^^x2, try to adjust the idle spark to get as much vac as you can
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Re: possible mechanical causes of erratic Idle??

Unread postby BongoBob » Thu Apr 09, 2015 2:02 pm

with the distributor ?or the tweecer. I hate to play with the tune since its so good right now ...except the idle. The wideband says the fuel is rich when and if the problem is occurring.Seems to be good ist start am but when I pull of the hiway to the stop it will usually go nuts !! Thanks again Bob
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Posts: 93
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Vehicle Information: 93 Lightning Wrecked the last one This one stock as far as I can tell except for FRPP (powerdyne) blower kit and Pro-m/dunnerite mass air conversion. Has Banks tc200 trans controller 24lb injectors and a Ford Cobra 24lb mass air meter. Using unchipped a9l for engine control and stock c3p1 for the transmission wideband by innovate
Vehicle 2 Information: FFR Roadster 408w mas flo Tremec 5speed ,moser axles worked dart heads
Vehicle 3 Information: Craftsman lawn mower 21hp r r r home made ram air

Re: possible mechanical causes of erratic Idle??

Unread postby decipha » Thu Apr 09, 2015 2:09 pm

with the tune, NEVER adjust the distributor set it at 10 and forget it

kick up the idle spark
reduce the idle VE
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Re: possible mechanical causes of erratic Idle??

Unread postby red5.0fogger » Thu Apr 09, 2015 3:38 pm

How crazy is the custom cam? Have specs for it?
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Re: possible mechanical causes of erratic Idle??

Unread postby BongoBob » Thu Apr 09, 2015 4:44 pm

yeah it's not too nuts at all , its just a little smaller and with a wider lobe separation than the one in my 408.That one idles great at 850-900 but it's in a mass air car. The specs for this one are 576/600 242-248@.050 on a 112 centerline +4 degrees. This is a weird problem I almost think I hear a switch go off and then it goes to pot. usually only hot. Tomorrow I will put a vacuum gauge on it. Decipha said he saw 26" of vacuum in the log I posted in the other tune post . before I had the tune adjusted Also installing the closed breather with hose to the tb tomorrow. I datalogged this and do not see the problem , that's why I say mechanical issue. Also going to give up on the smoke test and try propane around the injector o rings and intake. Then its parts swap time , iac/map/egr block off plate even though none of it appears to be causing a problem Thanks , Bob
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Vehicle Information: 93 Lightning Wrecked the last one This one stock as far as I can tell except for FRPP (powerdyne) blower kit and Pro-m/dunnerite mass air conversion. Has Banks tc200 trans controller 24lb injectors and a Ford Cobra 24lb mass air meter. Using unchipped a9l for engine control and stock c3p1 for the transmission wideband by innovate
Vehicle 2 Information: FFR Roadster 408w mas flo Tremec 5speed ,moser axles worked dart heads
Vehicle 3 Information: Craftsman lawn mower 21hp r r r home made ram air

Re: possible mechanical causes of erratic Idle??

Unread postby red5.0fogger » Thu Apr 09, 2015 6:25 pm

Something is screwy with a reading of 26 inch of vac. That's a pretty lumpy cam in my eyes. I say no way should it pull 26 inches. That's more than a stock pick up would pull. Smaller cams pull more vacuum at idle. They make more bottom end and idle smoother and make less peak power.
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Re: possible mechanical causes of erratic Idle??

Unread postby decipha » Thu Apr 09, 2015 6:37 pm

I think youve got me mixed up, ive never said i seen 26inches of vac ever, that almost defies physics

the smallest of smallest cams at most may suck down 19" on a healthy engine, anymore than that is highly unusual

most any peformance cam is going to suck down less than 15" or so
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91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
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02 Harley F-150 - Sasasha
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00 Explorer 5L - Bernyce

Re: possible mechanical causes of erratic Idle??

Unread postby red5.0fogger » Thu Apr 09, 2015 6:51 pm

No biggy I think something got lost in translation. I wasn't callin you out. Just the data seemed wrong
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Re: possible mechanical causes of erratic Idle??

Unread postby decipha » Thu Apr 09, 2015 7:02 pm

yea i think hes referring to kpa
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91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce

Re: possible mechanical causes of erratic Idle??

Unread postby BongoBob » Fri Apr 10, 2015 5:03 pm

Im old I probably reads it wrong and caused the confusion on the 26" or kpa . The cam should idle at 1k rpm and it does sometimes . However after a ride to or from work 26 miles it will either be 1500 or so , or do the alcohol funny car idle and will stall. When it idles right the wb gage is 14.7-14.8 when the idle is low and stalling it reads 12-13. I've got a vac gage here a handheld vac tester and propane . first I'm going to correct the breather , then install the egr blockoff clear the kam and ride . Then vac test the regulator it seems to work the pressure goes down with the hose on. I know the tb shafts leak we visited that previously.Cant really afford the Accufab 75mm right now + I can't find my spare tb. ther is a cheap 75mm tb out there for 120 ish but it might be crap. Just a note of something I remembered before the change back to sd I had to install a toggle and diode for the converter lockup? Wonder if that's screwing me up. Any way Sat is the day for this . I will report back with findings , if anyone thinks of anything please post I have to fix this . Thanks again Bob
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Vehicle Information: 93 Lightning Wrecked the last one This one stock as far as I can tell except for FRPP (powerdyne) blower kit and Pro-m/dunnerite mass air conversion. Has Banks tc200 trans controller 24lb injectors and a Ford Cobra 24lb mass air meter. Using unchipped a9l for engine control and stock c3p1 for the transmission wideband by innovate
Vehicle 2 Information: FFR Roadster 408w mas flo Tremec 5speed ,moser axles worked dart heads
Vehicle 3 Information: Craftsman lawn mower 21hp r r r home made ram air

Re: possible mechanical causes of erratic Idle??

Unread postby red5.0fogger » Fri Apr 10, 2015 5:23 pm

You can lightly spray suspected areas with brake cleaner. If the idle changes its a sign of a leak. Good luck.
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Re: possible mechanical causes of erratic Idle??

Unread postby BongoBob » Sun Apr 12, 2015 3:35 pm

Ahh success !! or so I thought ! I tested everything connected to the intake to verify it all held vacuum with the handheld pump and....found the map sensor would not hold any vacuum !! I replaced that and re did the breather set up then fired it up .Was good cold but as soon as it got to temp low idle and stalling. I did clear the kam . so A road test and I came back and had a 1500 idle in drive .I held the brake and then after a few seconds low idle and died . Thinking an adjustment to the stop screw may be required due to the failed map I re did idle 101 , same thing! I did find that when I adjusted the stop screw to lower the idle , the rpm went up. The only time I've ever seen that happen is when the throttle shaft moves in the bore, and it does . So I guess I have to go there next . Red o5 and Decipha thanks for the input .
BongoBob
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Posts: 93
Joined: Sat Mar 28, 2015 9:48 am
Vehicle Information: 93 Lightning Wrecked the last one This one stock as far as I can tell except for FRPP (powerdyne) blower kit and Pro-m/dunnerite mass air conversion. Has Banks tc200 trans controller 24lb injectors and a Ford Cobra 24lb mass air meter. Using unchipped a9l for engine control and stock c3p1 for the transmission wideband by innovate
Vehicle 2 Information: FFR Roadster 408w mas flo Tremec 5speed ,moser axles worked dart heads
Vehicle 3 Information: Craftsman lawn mower 21hp r r r home made ram air

Re: possible mechanical causes of erratic Idle?? fixed!

Unread postby BongoBob » Fri Apr 17, 2015 5:42 pm

Ok so here is the deal , I'm old , got a mortgage like everyone else but have to go fast .!!! I picked up a used 55 mm tb/iac/idle air plate/egr spacer for 25 bucks . cleaned it up and installed . My idle now only varies by 200 rpm instead of all over the board , the stalling is fixed , but I lost power . -25mm on tb size will do it This is with no other adjustments and I haven't cleared the kam yet . I also found new bearings for the leaky 75mm bbk tb. I'm off to update that thread now . Thanks for the help and patience Bob.
ps yes its down on power with the smaller tb
BongoBob
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Posts: 93
Joined: Sat Mar 28, 2015 9:48 am
Vehicle Information: 93 Lightning Wrecked the last one This one stock as far as I can tell except for FRPP (powerdyne) blower kit and Pro-m/dunnerite mass air conversion. Has Banks tc200 trans controller 24lb injectors and a Ford Cobra 24lb mass air meter. Using unchipped a9l for engine control and stock c3p1 for the transmission wideband by innovate
Vehicle 2 Information: FFR Roadster 408w mas flo Tremec 5speed ,moser axles worked dart heads
Vehicle 3 Information: Craftsman lawn mower 21hp r r r home made ram air

Re: possible mechanical causes of erratic Idle?? fixed!

Unread postby decipha » Fri Apr 17, 2015 5:51 pm

yea 400 cubic inch engines typically like to breathe lol

good job on the find, once you get her situated itll make it much easier to dial her in
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Vehicle Information: Supercoupin' x10
90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce


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