rpms drop after a drive on a HOT day

[tturbolife1]

so now that the beautiful sun is warming things up in NJ iv been noticing once i start my car, my rpms are around 1300 after i take it for a drive and the water temp goes up to 210 and steadys my rpms drops to around 750 and 680 when i turn the headlights on?! my vac is 20 A/F is 14.4-15.3 (aem wideband) i have a fmic 24x12x3.. which should be big enought to cool my air down while i drive so i dont get it. i tried to play around with my BISS raised the rpms but they still drop to the 700s. anyone have any suggestions. i also unplugged the ECT so the fans would be constantly running but i still get the same thing. only when the car is hot it happends.
all my parts are listed in my profile, i use 93 oct , no AC, never overheats though

im running royal purple btw. anyone have any suggestions?

 

[muleunit]

Check your base timing

 

[born2tune]

actually you might be overthinking it to hard, i think your alternator is bad.

 

[tturbolife1]

i did have a bad alt. and i replaced it with a refurbished one about 1 week ago now i cant even begin to tell you what a difference it has made. the batt light and brake light used to stay on while i was driving and i wouldnt even go over 50mph , it would just stall. could the alt be getting too hot?

 

[born2tune]

i did have a bad alt. and i replaced it with a refurbished one about 1 week ago now i cant even begin to tell you what a difference it has made. the batt light and brake light used to stay on while i was driving and i wouldnt even go over 50mph , it would just stall. could the alt be getting too hot?

ive gone thru the same symptoms you are having by the T!

except my eng overheated, which has not happened to you, what happened to me was that the belt broke that drives the water pump, powersteering...

but with the 50mph thing, what happened to me was an intercooler pipe that popped off with out me noticing, (and it was my forst time so i had no idea where to even look @or what it really was) it lost all its power, bogged down and couldnt pass 2k rpm then on fifth gear didnt go over 46-50mph...

doesnt seem like this is the reason for your problem but just letting you know, so you can put all the pieces together to pin point whats wrong

good luck

 

[debbie]

What about your battery?
If your alternator was bad then it might have damaged your battery in the process.
Or it could just need topping up with distilled water and given a bit of a charge.

ive gone thru the same symptoms you are having by the T!

except my eng overheated, which has not happened to you, what happened to me was that the belt broke that drives the water pump, powersteering...

but with the 50mph thing, what happened to me was an intercooler pipe that popped off with out me noticing, (and it was my forst time so i had no idea where to even look @or what it really was) it lost all its power, bogged down and couldnt pass 2k rpm then on fifth gear didnt go over 46-50mph...

doesnt seem like this is the reason for your problem but just letting you know, so you can put all the pieces together to pin point whats wrong

good luck

Its the timing belt that drives the water pump.

There is another belt that drive the power steering

 

[born2tune]

What about your battery?
If your alternator was bad then it might have damaged your battery in the process.
Or it could just need topping up with distilled water and given a bit of a charge.



Its the timing belt that drives the water pump.

There is another belt that drive the power steering

oh snap, thnx for catching my mistake.

 

[tturbolife1]

i did have a bad alt. and i replaced it with a refurbished one about 1 week ago now i cant even begin to tell you what a difference it has made. the batt light and brake light used to stay on while i was driving and i wouldnt even go over 50mph , it would just stall. could the alt be getting too hot?

after the new alt i can go as fast as i want, but still i want to bring my idle up i tried to bring it up with the biss and safcII

and the bad alt did mess up my batt , so i was forced to buy a new one.In the winter it was fine i would drive and drive and still never have this problem. do you think it could be the heat the or air density?

 

[born2tune]

now you might be thinking to hard again, it sounds like a vacuum leak. because when someone pulls off their brake booster hose it idle rough (hence a vacuum leak) so look for that and anywhere else that creates vacuum....

 

[tturbolife1]

even tho my vac is 21 on my boost gauge at idle?

 

[turboglenn]

Deffinitely some overthinking going on... anytime the alternator needs to produce more voltage to charge the battery (decided by the regulator)it takes more power to turn it and thus loads the engien down bringing the idle with it..

Now the car SHOULD correct it's self but if it's not i would look into cracked or unhooked vacuum lines, an miss-adjusted BISS screw, BOV not recirced... there could be a few things causing it but it's probably going to be one of those little "does no harm but is a huge headache to solve" issues and it will undoubtedly be something super simple or you'd be getting a check engine light or noticing other issues along with the drop in idle... the ISC should be bringing the idle back up so start there .. unplug it while the engine is running and see what happens, if there's no change in the car's running then there's an issue with either the ISC or the wires to it... they are common for having issues (at least IMO) sometimes the "cap" on the tip can pop off leaving it uselss to controll idle (this happened on my 97 gst back when i only had a 16g)

Plug the ECT back in, it does much much more than just turning fans on..... if you want control of the fans, take pin 20 at the ecu and either cut it or splice into it and run a switch that when turned on connects the wire from pin 20 to ground, that turns on the main fan on "hi" for sure, and i THINK it puts the condensor fan on low at the same time but i can't recall exactly right now... My pin 20 is on a toggle switch as i type this

Its the timing belt that drives the water pump.

There is another belt that drive the power steering

the timing belt does NOT drive the water pump, it goes around it, the water pump is run by the same belt as the alternator, and the power steering is driven from the waterpumps second pulley

 

[tturbolife1]

hmm. now i just got back from a drive on the highway. i would step on the gas and the rpms would stutter and just stay there. the car didnt move wouldnt boost . kinda sounded like a drum roll, then i looked at my wideband. it was LEAN i only saw(-----) then i would switch gears and it would be fine. then if i stayed at a certain speed for a while and tried to boost it would happen again. im gonna take a closer look at it tomorw. as for rite now do you think it could be tied together with my original problem or are they 2 separate problems?

 

[turboglenn]

To be honest they could very well be related, and while typing this and thinking how they could be related a little cartoon style lightbulb popped on above my head. WHEN was teh last time YOU changed the fuel filter? And i don't mean "the guy who sold it said it was replaced xxx ago" i mean you doing it yourself?

And ya know how things happen in 3's, well this would be the third fuel filter issue i've seenj since last week so if you haven't changed your check on it cause it could certainly throw things out enough to effect the idle if it's really dirty, and could impeed flow enough to cause that lean gasping sputter as well... and right before that bulb above my head fizzled out one more thing it brought to mind was your TPS sensor and is it good and properly set? If it's bad that could participate in your stuttering and could easily cause the idle issue if not set correctly (being bad would throw a CEL but not set properly really doesn't usually)

so get on those 2 and get back to me, if anything else pops up i'll post it for ya to check as well

But before i keep tossing things out i'm going to ask that you check what i've mentioned first and report back... i say this because a million times i've seen advbice given or given it myself and some one says "yea, i checked that and it was fine" then i go over (or some other wrench head) and we find out it was one of the first thigns we brought up but the owner thoughght "nah, it can't be that" and skipped over it making us all keep thinking and giving out ideas to some one who wouldn't listen (no offense intended but not knowin ya, i'm gonna hold off and wait for some reports back before i keep firing out ideas )

 

[tturbolife1]

fuel filter is new, not even 500 miles on it changed by,me. and now that i think about it one of my last posts was about frying my power transister. and i did that by leaving a power wire open and it curled and touched the intercooler pipe which blew my PT i changed that and now its fine. so maybe i fryed the other components also?

 

[turboglenn]

aha... that's what i like to see.. some one who can remember when they last chenged filters and fluids ( i tell ya i know and meet people all the time that are like ... "my car doestn' really burn oil so i don't check it but i have the shop change it about once a year" ) all i can do is shake my head... but since you've ruled yourself out of that category we can keep moving on

Check that ISC just to see.. although it may be related they may not, so unplug it with the car running and see if the idle changes (car should almost stall)

A lack of ISC will cause the idle you're talking about ...see it a lot on cars with SMIM's where the owner didn't take the time to implement an ISC device of any sorts, manare you getting any check engine lights at all?

COuld be the MAF but that would trigger CEL's like crazy i would think. (being stand alone i only have a few sensors to worry about the CAS, IAT, ECT, MAP, and TPS ) if they check good then it's just checking the coil, transistor and then hard parts.. sortring out factory ECU cars is much more a PITA but none the less i do them all the time

 

[tturbolife1]

I do have CEL because i unplugged my ECT now my logger ran outa batt. and i cant even use it because the computer that had the software on it crashed! il check all thos points tomrow after i put on my new drilled and slotted rotors and new pads!!!!!!!!!!!

 

[turboglenn]

plug your ECT back in ASAP, it will hurt more than you think on your OBD-II ECU

then reset the ECU by unplugging the battery or whatever method you prefer

do these before going any further

 

[tturbolife1]

well i took a video of what happend when i unplugged the tps and isc im gonna try and upload it now

http://www.youtube.com/my_videos

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/F9kn66sCZwo&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/F9kn66sCZwo&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

this is with my ECT in.

i did drive it around to brake in the new rotors and it didnt happen again. it was idleing in the 1000s this time.. what was the mod you were talking about turboglenn? it lets you control the fan relay?

 

[tturbolife1]

what does this mean?

 

[tturbolife1]

nothing??