up and down blms !!!

M

mattsTurboT

New Member
Joined
Jan 5, 2004
hey guys.. i got an 87 turbo t. car idles at 1000 in warm up mode then drops to 750 and bounces back up to 900-1000.. and continues bouncing from 750-1000... 00 iac counts at idle. and good counts at cruising.. 145-160 counts BLM.. altho when i hit the gas it blms quickly start dropping off sometimes to around 98-110 then as i steady out my speed they start rising to 125-135blms. new check valves and vacuum lines. fuel pressure at 40 psi no vacuum. i just changed out my 152k mile egr solenoid for a 125k mile solenoid i got from a buddy and it did seem like it got worse after that. this solenoid is newer and cleaner and all the o rings are perfect. the vaccum line going to the charcoal canister was so dry rotted between the sensor and the check valce that it sucked together.. i replaced that whole line and tested the check valve... disconnected the line while running, no change in park idle blms or iac.. i tried adjusting the iac but i turned the screw as far as i could go without breaking the spring in between the bolt head and the bracket and could only get 6 iac count. :( ? should i take the spring out? why would the blms be pegged at idle and then fall back to the between 98-115? i know i have a coolant leak on front of the intake.. wondering if air can leak from there.

also wondering if my oil pump is going bad. with engine running with the driver side cover off i see no oil flow. just oil residue on the springs?

thanks in advance guys
 
what kind of chip, fuel pump & injectors do you have?

where's your tps at?

High BLM's is tuff to diag but needs to be fixed....

The hunting could be a bad maf also, did you have a new style maf with translator? Driver side header is it cracked?

During my diagnoses , I was blaming evrything under the hood and it was a simple fix
 
I can't answer all your questions, but I did notice your 0 iac. The IAC count is the command the ECM is giving the IAC valve to maintain idle. When it's 0, then the IAC valve is not being "ordered" to open so the ECM can maintain 750 RPM. Essentially, the ECM has no control over idle when IAC is 0 (can't get it down to 750), and conversely if the IAC is high (> 40) then the ECM is overworking the IAC to keep idle up to 750. You need to back the set screw off so the throttle blade closes more. Your idle will fall, then the ECM will command more IAC, and you will see higher numbers. Of course if you have vac leaks, then it all goes to hell, and will make it 0. Remember to check IAC in park with all accessories off, and check your TPS when done. You may have to repeat a few times. I belive IAC counts when cruising mean nothing.

I've never watched BLMs when throttling hard, just during cruise, and your range appears OK there. You might want to bump the fuel pressure a bit, but that depends on your chip.

I'd also do a thorough re-check for vac leaks.
 
Originally posted by mattsTurboT
i tried adjusting the iac but i turned the screw as far as i could go without breaking the spring in between the bolt head and the bracket and could only get 6 iac count. :( ? should i take the spring out?
Click to expand...
If the IAC counts are 0 you don't want to screw the throttle screw in, you want to back it out to close the throttle blades and thus make the IAC open so the ECM can control idle.
If you had some dry rotted vac lines, I'd say replace all of them, check especially behind the intake, seems to be a couple of check valves back in that area that have a tendency to separate from the hose.
 
thanks

hey guys thanks for the info.. i correctly adjusted my iac and tps now. bad news is i found the problem.. cracked driver side header.. i can hear it pretty good too.. i was thinking should i get a used one off line like turbo trader or parts for sale forum , one thats been cracked and welded or one that hasnt cracked yet.. look like im gonna have to spend anywhere from 50-100 bbucks for a set or just one.. thanks alot guys. ur a big help for my everyday troubles :p
 
just get yours welded fixed, probably the fastest way to get it done.

I brought mine to a muffler guy for a reweld, so far its been 3-4 months still holding...
 
welding header

hey thanks for the quick reply.. i heard u are supposed to have the header attached to a head when for it to be welded correctly and not bend out of shape or whatever...i dont want to take off the head.. its my daily driver and i dont have enuf time to take off the head. if it could be welded correctly without a head attached i would do that. otherwise ill buy one from some one off the net. but i better hurry up.. not good having blms sometimes pegged at 160 :mad: :eek: scary
 
My redneck non-pro buddy welded my DS header 2 years ago (it was cracked 75% around). So far, so good.
 
BLM's are long term corrections and dont move that fast. What you are witnessing is the ECM accessing different cells depending on operating parameters. IOW, at idle under 800rpm, you;re accessing cell 0, which may be some value, over 800 is cell 1, which may be another value, over 1100 another value, different load, another value. and so on. If you're watching on say Scanmaster, it doesnt indicate what BLM cell you are in, and I'm not sure the TR data stream will even tell you. It appears that the BLM's change, but they are not. As long as none of the cells are maxed either way, dont worry about it. If you want to get all the cells to 128, it will take messing with the MAF tables, assuming the engine mechanically is in tip top shape. As far as raising the IAC counts, you're going the wrong way. min air goes UP (screw in) IAC comes down, as the ECM tries to LOWER the RPM, and visa versa, the screw is backed out, the ECM tries to RAISE the idle

Looking at your rolling idle, low IAC, high BLM I'd bet you have some sort of vacuum leak. ANd the off idle BLM's are so low because you got the FP cranked up to try and bring the idle BLM's down that the car goes rich once the throttle airflow is greater than the vacuum leak airflow. This is one reason I tell guys there is an accepted RANGE of fuel pressure. Above or that or below that there is a problem with the car. IMHO, FP should be between 32-38psi (vac on), more or less, theres a mechanical problem, or calibration problem.

Again, thats only MY opinion, and many do not share it.
 
Did you check your pcv valve? Even if its good or has been replaced it has to be ac delco or you will have high blms. Ac delco one is a nasty green color.
 
pcv

yes i just recently within the month put a new ac delco pcv in...as i stated above the DRIVER side HEADER is cracked.. i can hear it pretty good.havent seen the crack yet but i know it must be cracked if i can hear the loud ticking right at the manifold... ill check again and see if i can find it with a flashlight...



anyone know if header can be repair without being attached to a head and not get bent out of shape.. ???
 
HELP!!!!!!!!!!!!

My IAC count in park is 89. I've tried upping the idle to get it to lower, but it raises as the idle goes up.. The idle is at 1k all the time, and the set screw is backed out completely. The idle varies a little bit 950-1000 rpm. TPS is .46. What could be the problem... Its running and driving quite well, we even just converted the LS1 MAF to "blow through", which I strongly suggest. My mods include, Translator, 009's, EGR tower removed/filled, gasket matched ports, stock headers, stock turbo till we figure this bs out, 3" integral dp, underdrive pulleys, adj wastegate, Comp 212 cam... HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
Re: HELP!!!!!!!!!!!!

Originally posted by Spooled85gn
My IAC count in park is 89. I've tried upping the idle to get it to lower, but it raises as the idle goes up.. The idle is at 1k all the time, and the set screw is backed out completely. The idle varies a little bit 950-1000 rpm. TPS is .46. What could be the problem... Its running and driving quite well, we even just converted the LS1 MAF to "blow through", which I strongly suggest. My mods include, Translator, 009's, EGR tower removed/filled, gasket matched ports, stock headers, stock turbo till we figure this bs out, 3" integral dp, underdrive pulleys, adj wastegate, Comp 212 cam... HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Click to expand...

I'd start by setting the TPS a bit lower. Here's a good read
It's possible the ECM isn't recognizing your setting as idle. Same site as above has good info in IAC adjustment, among others.
 
Thanks for reply

Well, we're in spec now... .18 IAC .44 TPS, but now the rpms are at 1000 in park.. in drive off the gas its like 1500, any ideas? I dont know what the problem could be... People are saying the chips telling the computer this??
 
If those items are in spec, then I'd also suspect the chip. The idle speed is programmed. Take a look thru Steve's website that I posted the link. Some very interesting info I didn't previously understand. Pick up a thrasher for 25 clams, cheap check.
 
Thanks

That website you gave me only has this on its page....

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See what you can do... Also does the Thrasher chip work with 009's
 
Bolt it down

I used a very straight 4X4 wood block and bolted mine down with lag bolts. Welded it,sandblasted and repainted :D used felpro exhaust gaskets. No problem since repaired 8 months ago.
 
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