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So easy cavemen can do it
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Discussion Starter · #1 ·
What else do I have to do? First thing I did was unscrew the old IAC valve a little bit because I don't have a scan tool to exactly see where it should be...the SLIGHTEST turn I made...the car wouldn't even idle when I started it up...I took the thing completely out and cleaned the hell out of it and the hole...put the screw back in all the way and still no idle...got a NEW IAC valve and car idles again but I still get a horrible up and down cold start idle...idles fine when warm...new MAF sensor and no leaks or anything in any vacuum lines...does anyone have a clue as to what else could be causing this? my fuel pressure is set at 46 psi line off...
 

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A question, when did the cold idle problem
start?

You may find someone with another chip or if you have another chip you may want to try it
when the car is cold and see if that makes a difference.

Take Care

Neal
 

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Fuhgeddaboudit
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18,613 Posts
If you dont have a scantool the the thing you do us get a scan tool.... Fuel pressure of 46psi is high unless you have a thrasher chip. This is the manual way. its close :
1. Ground ALDL diagnostic lead (short the top two rightmost pins in the ALDL connector).
2. Turn on the ignition (but don't start the car).
3. Wait 30 seconds.
4. Leave ignition on and disconnect the IAC connector.
5. Remove the grounding from the ALDL connector.
6. Start the car. The car will probably run rough and may stall. Just restart and try again.
7. Adjust the throttle stop screw to set the idle to 500 RPM +/- 50 RPM.
8. Turn the car off and reconnect the IAC connector.
9. Turn ignition on and adjust TPS to proper settings. (.42-.44 at idle is typical)
10. Repeat procedure until the 500 RPM +/- 50 RPM in step 7 can be maintained while TPS is at proper idle setting.


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ED BAKER
87-T-TYPE, PT54,MSD50's,Crane Billet Roller,JE forged20over,P&P Heads,Manley valves,Hemco 65mm& Acu65TB,V2 FM, P.I.9.5 -7disc,Jimmys Trans, new times soon.
93 PARK AVE"SUPERCHARGED"
67RS/SS350 CAMARO
mailto:[email protected][email protected]</A>
http://www.modernmusclecar.net
 

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So easy cavemen can do it
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534 Posts
Discussion Starter · #4 ·
seems whenever i try to adjust it...the cold start idle is always the same "horrible"...i set the idle a little higher now and idles great at a stop when warmed up...but it's just when i cold start the engine...it's been doing this for 5 years and i could never figure out how to fix it...i have tried everything known to man and even a chip change doesn't help...new o2 sensor as well...don't know what to do other than just not drive it anymore in the winter!!! sigh...i'll just have to live with it

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new webpage being made, should be up soon with new pics

1987 Buick Grand National (owner since 1997) - 77,000 miles, everyday driver (rain, sleet, hail, snow, its seen it all) engine never opened up, basic bolt on upgrades include:

Cold-air induction w/ 9" K&N air filter behind headlights, Accufab adj. fuel regulator (set at 46 psi), Thrasher 92 street chip w/anti-theft, Walbro GSS 307 fuel pump w/ Casper's hotwire upgrade kit, adj. wastegate actuator (set at 18 lbs), transmission cooler, 160 degree thermostat, tb coolant lines blocked, 3" Poston's DP w/ 2.5" Hooker exhaust & AeroChamber mufflers, 3" hi-flow CAT, basic chrome engine dressup items, stock rims on BF Goodrich P255/60/R15 all-weather rear tires, newer paint, 30lb VDO boost gauge and 100psi fuel gauge

first track times ever this spring:)

Note to all Ford/Import owners: BUICK OWNZ J00;)
 

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43,735 Posts
You got a vacuum leak?

Maybe between the plenum aNd intake? Pvc? under the vacuum block (between the block and plenum)
 

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So easy cavemen can do it
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534 Posts
Discussion Starter · #7 ·
no vacuum leaks to my knowledge and has done this through 3 different maf sensors...

------------------
new webpage being made, should be up soon with new pics

1987 Buick Grand National (owner since 1997) - 77,000 miles, everyday driver (rain, sleet, hail, snow, its seen it all) engine never opened up, basic bolt on upgrades include:

Cold-air induction w/ 9" K&N air filter behind headlights, Accufab adj. fuel regulator (set at 46 psi), Thrasher 92 street chip w/anti-theft, Walbro GSS 307 fuel pump w/ Casper's hotwire upgrade kit, adj. wastegate actuator (set at 18 lbs), transmission cooler, 160 degree thermostat, tb coolant lines blocked, 3" Poston's DP w/ 2.5" Hooker exhaust & AeroChamber mufflers, 3" hi-flow CAT, basic chrome engine dressup items, stock rims on BF Goodrich P255/60/R15 all-weather rear tires, newer paint, 30lb VDO boost gauge and 100psi fuel gauge

first track times ever this spring


Note to all Ford/Import owners: BUICK OWNZ J00


[This message has been edited by d0n_3d (edited January 16, 2002).]
 

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Premium Member
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43,735 Posts
I would really check for vacuum leaks and also a bad egr gasket.
 

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Fuhgeddaboudit
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18,613 Posts
A local here was having idle trouble with the thrasher chip. Swap back in the stock chip (if you have stock injectors) and lower fuel to 42psi. Then try again. Also as said above EGR valve. pull up and down on the plunger make sure it travels free.

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ED BAKER
87-T-TYPE, PT54,MSD50's,Crane Billet Roller,JE forged20over,P&P Heads,Manley valves,Hemco 65mm& Acu65TB,V2 FM, P.I.9.5 -7disc,Jimmys Trans, new times soon.
93 PARK AVE"SUPERCHARGED"
67RS/SS350 CAMARO
mailto:[email protected][email protected]</A>
http://www.modernmusclecar.net
 

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So easy cavemen can do it
Joined
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534 Posts
Discussion Starter · #10 ·
checked the egr...car did stumble a bit when pressing up and down on the diagphragm...also tried with both stock and thrasher chips and still the same exact idle problem...

so what i did was adjust the throttle stop screw some and also replaced the IAC with a new one and i started it up this morning and the up and down idle is gone...car will run at almost near 2000 rpms (stock tach) and then after a little warmup, dip into the 1000 rpm range...when i shut the car off then start it back up...the idle is kinda rough (assuming i am in open loop?) but once i get it back on the road...it will idle fine at 1000 rpms again...eh i'll take it


------------------
new webpage being made, should be up soon with new pics

1987 Buick Grand National (owner since 1997) - 77,000 miles, everyday driver (rain, sleet, hail, snow, its seen it all) engine never opened up, basic bolt on upgrades include:

Cold-air induction w/ 9" K&N air filter behind headlights, Accufab adj. fuel regulator (set at 46 psi), Thrasher 92 street chip w/anti-theft, Walbro GSS 307 fuel pump w/ Casper's hotwire upgrade kit, adj. wastegate actuator (set at 18 lbs), transmission cooler, 160 degree thermostat, tb coolant lines blocked, 3" Poston's DP w/ 2.5" Hooker exhaust & AeroChamber mufflers, 3" hi-flow CAT, basic chrome engine dressup items, stock rims on BF Goodrich P255/60/R15 all-weather rear tires, newer paint, 30lb VDO boost gauge and 100psi fuel gauge

first track times ever this spring:)

Note to all Ford/Import owners: BUICK OWNZ J00;)
 

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1,797 Posts
Do you have a scan tool?
If so, tell us what the IAC, TPS, GPS, BLM #'s are.
If you don't, you really need to get one, or at least borrow one to accurately set your IAC and TPS.
Remember the idle #'s are set in the chip, and it communicates with the ECM to adjust the IAC to give the proper idle RPM. Trying to adjust the idle by messing with the butterfly screw, just makes it harder for the ECM ( I'm not saying that it doesn't have an effect, just that it should be used for fine tuning adjustment of the IAC)

Follow ULYCYC's directions, and if you still have a problem, you know you will have to look elsewere for the problem. (Vac, PCV, EGR, grounds, etc.)

Paul


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1972 Toyota Celica with a 87 TR drive train.

PTE 44 turbo @ 20psi on pump gas. Jay Jackson’s 62 mm throttle body, ported and polished plenum and intercooler. Solid MAF pipe, K&N Filter. Blue tops. Hot wired 255 L/hr Holley inline FP., AFR. AC CR43’s. Type II coil pack and module. 8.5 Magnecor’s. Hand made TH style DP, 3” exhaust split to two 2 ½ inch Magnaflows.

Built 200 4R tranny, B&M cooler, stock D5 converter, B&M Megashifter.
Chopped Ford 9” four link setup @3:25 posi rear with a 300 ZX disk brake setup. Air bags, Bilstein Rally shocks.
85 Supra 57 mm piston 10” vented rotor front brake setup. Hurst Roll control. Tokico race struts, heavy duty coils. Nissan 300 ZX 15/16 master cylinder.
Dunlop SP 5000 205/50ZR 15’s, Ford power steering rack.

DirectScan, Caspers Knock gauge, Autometer 30/30 boost/vacuum gauge, Autometer tranny temp gauge. Jay C’s 94, Red’s 100, Thrasher 92, and my own chips
 

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One more simple thing to check is the egr filter. If it's dirty it will affect the idle characteristics. You can replace it cheaply or if nothing else, blow it out with an air compressor. My father's GN had a similiar problem & after cleaning this filter, it purred like a kitten. Good luck.
 

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I had this same problem" But the eng had to be rebuilt so I just let it go & built the eng" Strange thing ' When I put it all back together the up & down idle was gone?? All I can figure is it was a poor contack some where in the eng compartment & it was corrected when I put it back together. So recheck all your eng wiring. Also I did extend the ground wires behind the pass side head" I also replaced the connector to the IAC. So check them to. I wasted a lot of $$ on sensors & such to' To no availe. The problem I had was a fast up & down idle for a minute or so then it went away. Started when it started getting cold out.

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To hell with 12's Im going for the 11's!


Keith Davis**86GN, Astroroof, DigDash' TTA crank, Ported polished heads & matched intake' Jay's 62mm TB/upper, V4 IC' TRW .30 forged pistons & PT51 Turbo, Manly SS valves, CC 206-206 cam' Postons headers, Orange stripe conv. THDP,2 1/2 exhaust' Hooker comp. mufflers' SMC alky,Boost command, Scanmaster2, MSD50 inj, SS MAF & translator' Nitto DR's 275/50/15, All the braces, All gauges VDO.
12.8 @ 102 is with stock setup no times for new setup yet.


 
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