Ever since I've had this car it's had quite an idle surge...with the old SO motor, it would stall while making k-turns, with the HO motor it would load and unload the suspension at stops and would surge erratically while in park or neutral.
I went to Ford and ordered their "engine idle air kit", apparently there was a TSB for these things and this is the Ford fix. It is part # F2PZ-9F939-A. It cost me 43 bucks and change from Holman Ford(which seems to be the MOST expensive Ford dealership around). I know that Mustangs Unlimited used to carry basically the same thing for like $18.
So, now my car idles almost perfect...in park or neutral, warmed up, it idles around 900rpm(which is higher than I like but proved to be the best adjustment for idle in gear). While in gear it will idle around 700-750rpm. After being in gear for a few moments, it will surge around between 600-700 but it doesn't even think about loading the suspension...I still have to set the throttle stop screw according to the directions, so that could further improve the situation.
I just figured I would post this in case anybody else has the same problem and was looking for a remedy.
Hate to tell you this but... Cleaning the throttlebody & IAB, setting the idle to 600-700 rpm with the IAB disconnected and finally setting the TPS for .8-.9v would have done the same thing...
If it still surges at that point repl the IAB...
Oh well, I guess I just have another shiny piece under the hood...lol. It has a new IAC, and the throttle body/throttle plate were just cleaned...I'll probably mess with it some more and see what happens.
my 86 does the same thing. http://www.foxtbirdcougarforums.com/showthread.php?t=8308
but what does iac and IAB and tbs and all those others stand for? and where are they
Hey TC50...I was on mustang-forums.com yesterday and read that when setting the TPS it should be more like .98-.99V...is there any difference in the ECU's(between say a '91 Mark VII and similar year stang) as far as where they like the TPS voltage? If you say set it to .8-.9V, I will, I was just curious as to the different ranges.
Thanks,
Don
mustang guys think .98-.99 is for "optimal performance", it makes no difference
get i always say from .90-.99 is good
Thanks, well, I'm looking for "optimum idling" lol Before I installed that idle adjustment plate...the idle speed would not increase when running the a/c or defrost(a/c clutch engaged) and it would just kinda bog...since I put the plate on it will bump the idle up a little bit when I'm in gear and at a stop. Which is what I thought it should do, but never did. lol Once the weather breaks here( nor' easter)I'll go ahead and check all that out and post my results...
Thanks Again,
Don
My anderson standalone won't even say the ecm is in it's idle table until .96v and wot at 4.60v,kinda hard to get it perfect,and the idle screw has to be set first or it's impossible to get both.
how do you adjust the TPS?
Okay, well I set the idle screw as recommended by Ford...withing .002" of the throttle lever, then 1/2 turn...it was idling at about 525rpm with the IAC disconnected. I checked the TPS voltage and was only getting .68V at best...I adjusted the TPS, and got as far as .74V in the stock sotted holes. I took off the TPS, elongated the holes slightly bolted it back on and set the idle screw until it was at approximately 650rpm and .92V. The car has a mind of it's own...at first it didn't surge but idled at 800rpm in gear and closer to 1200rpm in park or neutral....after shutting the car off and restarting it, it idles at 850rpm in park/neutral and about 700rpm in gear...and surging again.
I still have the "idle air kit" on the car but both air bleed screws are cranked down tight so it's as good as not even being there.
Apparently, it also turns out that my throttle body is of the "sludge tolerant" design, according to Ford...don't know if that makes a difference.
The program in a stock computer assigns(if that is the correct term), TPS voltages of below 1 volt as idle... It then "learns" this voltage and adjusts A/F ratio to 14.7 to 1(assuming the o2 sensors are functioning)(it takes a while after an adjustment is made, but basically the EEC compensates for whatever you do). IF the voltage is over 1v the EEC goes into accelerate mode and opens the IAC/IAB(whichever you want to call it), to increase engine speed so if you suddenly back off the throttle it doesn't die... The reasoning for setting the voltage at .99 is there is less travel of the throttle to go from idle to acceleration(yea you can really tell the difference that .005-.010 less pedal travel makes when you mash the gas...NOT...) Setting it at .8 is ok as is .95, just as long as it is below 1 volt with throttle closed(Ford specs say it should be between .6-.8).
If you haven't already, disconnect the battery cable for 15-20 minutes so the EEC can start fresh in learning your new settings...
If you are continuing to have idle problems, possibly you have other issues... Has it been scanned for codes???
What exactly is your setup???
I haven't disconnected the battery yet, but that was my next plan...no codes in koeo or koer. As for not noticing a small difference in the tps voltage...my car "sounds" more crisp through the exhaust.
I have a stock '91 HO from an LSC w/EEC from same vehicle. I have Flowtech full-length headers, off-road H-pipe, dynomax super turbo's dumped, MSD coil and Super Conductor wireset, Accel cap and rotor, K&N panel filter, and a shade over 14* advance.
I had a problem where I was running Autolite AR133's last summer(two ranges colder) and kept them in until winter...car ran so rich, it totally gummed up my EGR valve and fouled the O2 sensor in bank 2. I replaced the O2 sensor, egr valve, egr pos. sensor, and egr vacuum control solenoid. I also replaced the IAC about a week after all that...car ran a little better...continued to break up at about 4,000rpm...new wires/coil didn't help...MSD blaster coil/wireset cured it....oh yeah, and I did put the right plugs back in Autolite 25's gapped at .054"
Thanks,
Don
Well keep us posted on what finally fixes it I seem to be having a similar idle problem at the moment. Mine seems to idle fine when cold and starts messing up as it warms up. then it speeds up and drops really far on its own. We could possibly have some of the same things messed up
Just run it a few days, the EEC will relearn the TPS and it will sound like it's old self again... :D
I got tired of the EEC undoing my changes... I pulled the memory wire for the EEC a couple of years ago... Now every time I restart it has to start the learn cycle all over again(assuming it's set for more than 10-15 minutes)... I mentioned the idea to a buddy and he said Hell of a idea!!! Then immedeatly disconnected his...
I will give it a few days and post back on monday evening. I'll probably be disconnecting the battery tomorrow morning while I do some things around the house, then I'll drive the wheels off of it all weekend and see what happens.
thanks
Don
Well, the car is fine cold...as it was before. Once it starts to warm up, it will idle nicely for about a minute or so, then comes the surging, as it was before. I hate this friggin' thing!
mines doing a similar thing it idles real high then almost dies then revs itself way up the tries to go back to normal but almost dies and then revs itself way up. just surging up and down. but it doesnt do it while its cold. only after it startshiznitting operating temps. I did notice that messing with the TPS did make a difference but didnt totally fix it.
it use to be that the mounting holes in a tps were egg shaped. You could then loosen the screws and rotate it ccw or cw. Nowadays, it seems the tps holes are just plain jane round.
my remedy is to use a round file and egg the holes out and remount the tps. now i can tweek the tps and measure off the green wire to get below a volt.
yeah I got the eggshaped my problem is figuring out how to read volts on my multimeter
You guys seem to have the oppisite problem that I had... When cold(under 55*) mine surged badly and always died unless I kept on the throttle. That problem has mostly been eleminated with the switch to the A9L EEC...
Ronnie had some problems such as you are describing(mass air A9P EEC) and found the A/F ratio was varing from around 13 to over 17 to 1 when hot. After trying everything, replacing the EEC fixed it...
I don't want to say thats your problen, but if you can find one to try it may be worth the effort... The Lincoln EEC does have the cruse amplifier in the computer. IF that circuit is connected, there can be some odd happnings... Be sure pins 35, 38, and 41 are not connected to some other circuit...
You guys seem to have the oppisite problem that I had... When cold(under 55*) mine surged badly and always died unless I kept on the throttle. That problem has mostly been eleminated with the switch to the A9L EEC...
Ronnie had some problems such as you are describing(mass air A9P EEC) and found the A/F ratio was varing from around 13 to over 17 to 1 when hot. After trying everything, replacing the EEC fixed it...
I don't want to say thats your problen, but if you can find one to try it may be worth the effort... The Lincoln EEC does have the cruse amplifier in the computer. IF that circuit is connected, there can be some odd happnings... Be sure pins 35, 38, and 41 are not connected to some other circuit...
Okay, thanks.
Here's my idea for you:
More than 5 years ago, we found that our '88 Bird was surging both while at idle and also on the road. It was sporadic---would even roar at a stop... The local Ford place told us they could not identify the problem ($70 for nothing). We then went to a small specialty shop. Right off, he did a clean job of the injectors at the fuel rail (attached the appartus at the fuel rail). Problem solved. I believe the problem happens when an injector starts sputtering or mal behaving and thus the engine computer attempts to over correct that, causing the surge or otherwise. I will not put any cleaner in the gas tank because, in retrospect, I have done this preventive maintenance in the past--maybe causing this problem to happen? You would be amazed at the that builds up in the bottom of a fuel tank. Now, in five years+ since, the problem has not returned even though the shop guy told us that this is a common problem with older injector engines. I had this happen in my Ford 5.0 shortly after the TB--diagnosis. I have not used injector cleaning in the tanks since the TB problem--no problem since. Have you put any cleaners in your tank recently in the past?
Mine has just been swapped in so any cleaners I used in the past shouldn't be an issue on mine. But then I don't know if the person who had them before did. Anymore I don't use any cleaners or such other then Lucas Oil products. The reputation they have it shouldn't cause any problems
Yes I used some fuel additives, but I had the problem for quite some time and I already replaced the injectors...didn't help the surging. I was doing some driving last night just for the sake of it...I would say that 50% of the time that I was stopped at a light for an extended period of time, it was idling nicely at 600rpm in gear. Seems like when I ignored what the car was doing and paying attention to the conversation me and my friend were having it would be good...if I was watching the tach...it would surge...lol, car must have a mind of it's own.
Ok, a little more info that might or might not help. While driving today...it seemed to be idling nicely at 600rpm in gear at a stop after driving above 40 or so mph...if I let my foot off of the brake and let it roll forward a bit then stop...it would act up...if i popped it into neutral and revved it a little then popped it back into gear, it seemed to calm back down. It's a weird situation and I'm just trying to relay all the facts...wondering if my speedo being off could cause part of the problem...ECU getting a false reading from VSS? I don't know, just publicly thinking aloud...lol.
thanks again,
Don
not sure it rolls over into the V8 but I changed trannys behind the 3.8 that was in my car and the speedo was off and it didnt make a difference. I would think it wouldnt make a difference. Just a thought and its probably been covered I just skimmed over what all we've covered so far. pull the codes from the computer and see what youre popping up. My light isnt on but I have something wrong with my TPS, something called AIRB messing up, and something called AIRD messing up. Basically codes 14, 81,82, the AIRB and D Im guessing is the TAB and TAD sensors which I didnt hook up due to they looked like part of the emissions system which could be part of my problem. check yours and see what you get. My light doesnt even flicker when the cars running but it still pops codes up out of the computer. The only time my light has came on the EGR vacuum hose was unhooked.
What's your fuel system setup? Injector size, pump size, adjustable regulator or stock? Also if adjustable, whats the pressure at?
My car is completely clear of codes in both KOEO and KOER modes...my fuel system consists of 19lb/hr injectors, stock FPR, stock t-bird pump, '91 Lincoln ECU...yes it is a speed density HO.
I do have a fuel press. gauge where my schrader valve used to be...it's at roughly 32lbs w/vacuum and 42 lbs w/o vacuum...needle isn't steady either, like it used to be...flickers around within 2-3lbs all the time that I know of....that leads me to believe maybe a FPR or pump has seen better days...don't know.
Set the F/P to 39psi with the ign on and engine off. You can do this by grounding the tan/green wire on the EEC test plug. A lot of gages tend to fluctuate, I had the same problem with my first gage. It finally wore it's self out with all the jittering...
when i start mine up it runs1200 1400 tnd then drops down to 800 but after that it wants to drop to 400 or alittle lower and jump up to1400 again but if i keep my foot on the gas while it warms up so it revs at 1200 and then shift into gear its fine till i get to the end of my street and it wants to blog and struggle to move then it goes. but after i drive for a while it and go to back up in to the driveway it dies.
ok Im starting to think TurboCoupe50 might be onto something with the computer thing.
cougar86_89 which computer do you got?
I have an old V8 XR7 computer from an 88 or at least thats what the salvage yard or whoever had wrote on the case.
Sick88TBird has one from an LSC.
all this and we all have similar problems. where as people with say the A9L computers are running like theyre supposed to.
Could it be possible in some weird way that we have to have certain computers to make the 5.0 SEFI engines work in our cars? Not that I'm that eager for a reason to get a new computer just yet. But could it be possible until we get a certain computer we're going to have problems similar to these?
Probably gonna just have to deal with it...how does grounding that test wire bump up fuel pressure??? BTW, these are not sequential EFI engines xzavior.
Wrong answer.... ALL passenger car 5.0s are SEFI from '86-up. The trucks and vans were batch fire into the '90s...
Whoops, thought that applied to the passenger cars as well...I stand corrected. *inserts foot in mouth* boot leather doesn't really taste that bad...lol. Am I supposed to leave that tan/green wire grounded or just in a KOEO to set it up?
thanks,
Don
Just to set pressure KOEO... DO NOT LEAVE IT CONNECTED....
i have the stock computer in an 86 ls 5.0 i dont know anything esle about it *(declare ignorance)*. did different one come from the factory?
no but what Im thinking is if we've upgraded the engine, for example, HO intake, HO tb, new exhaust and so on and so on, could that be making a difference as it lets the engine get more airflow and able to breathe easier.
Could it be possible the older computers cant compensate for it totally?
Im actually pretty lost on what could be wrong but I have noticed a difference between people with newer computers and people with older and so on.
Well, my fuel pressure according to the rail mounted gauge sits at 38lbs, so I figured I didn't need to perform that procedure...I would check those pin locations at the PCM, its easy enough as it's laying on my floor...but I don't feel comfortable messing with that...knowing my luck something horrible would happen.
It SOUNDS like my EGR is opening/closing when it surges low...when inside the car, I hear a funny tone by the firewall when it surges low...right were the EGR is. I don't think that is normal, but I've proven a few posts ago that I DON'T know it all...lol. TurboCoupe50, I know I'm a PITA, but I greatly appreciate your time and knowledge.
Thanks again,
Don
Disconnect the vac to the EGR... It will run fine without it... If it still surges that ain't your problem... If your F/P is 38 psi with the vac line on the reg then it's too high... Set at 39 with NO vac, then try +/- a pound or two from that point...
The Speed Densety EECs can only compensate SLIGHTLY for engine changes... You may get away with a larger throttle body and/or exaust. But beyond that, airflow improvements will cause a lean condition at WOT. Larger injectors will cure that problem, but it will be pig rich at idle... Possibly a slight increase in F/P(with orig injectors) will be OK...
mine also makes a click noise put is isnt as load as a lifter like my dads car has put could that be part of the problem?
mine ticks too. could you happen to have an exhaust leak? my passenger side where the tail pipe meets the header is leaking and it sounds like a ticking or clicking sound. only reason I know its the exhaust is I can feel the air coming out if I put my hand by it. try when you first start it if you start looking for one though so you dont burn yourself.
Also are the stock HO and stock SO injectors the same size?
It's at 38lbs with the KOEO...at idle, with the vac connected it's at approx. 32-33lbs...at idle without the vac line connected it's at approx 42-43lbs.
I know for a fact the HO and SO injectors are different...stock HO injectors(not cobra) are 19lb/hr whereas SO injectors are 14lb/hr. I will try disconnecting the vacuum line to the EGR...I doubt it will help but it's easy enough to try....my full-length headers are of the "slip-fit primary" design and they leak a little...but the car was doing this well before I had those headers on. So, I don't think that a slight exhaust leak will cause such a problem.