Idle still rocks on lights, fan, brake, PS... with a 110AMP alternator

[Slavic]

So since the one I had running died I put a 110AMP Acura Legend alternator in expecting to get rid of my idle problem, but it's still there. If I step on the brake it rocks the idle a good 250-300 RPM up once it's depressed, headlights 50RPM, inside fan 100RPM, power steering (turn wheel left or right) 100-150RPM. I didn't check radiator fan, but I'm sure it still rocks the idle too. The idle settles in a 250 RPM range too depending on it's mood.

What gives?

In addition to that the car will still hesitate and idles erratically within a 100 RPM range sometimes and all this after putting in new spark plugs, a bunch of fuel system cleaner additives, air intake cleaner, seafoam into engine, PCV Valve hose and gas tank, B12 just for good measure, two cans of motor flush new fuel filter, air filter and I don't know what not.

It has a properly working fast idle valve (adjusted down, no longer partially blocked) as well as idle control solenoid (I think it's called) tested on another car and throws no codes. It's been getting 33 MPG too.

Also when I rev it it's very slow to come down.

It's an 87 LXi

[Vanilla Sky]

if you have a junkyard near, just for good measure, replace the IAC valve...

also, alternators don't put out too much power until a decent RPM... hell, rewinds usually make almost no power until about 2000 RPM... well, comparatively speaking...

does the LXi have a fast idle unloader, or is that just a carb thing [too lazy to look in the repair manual sitting about 6 feet from me]?

[Slavic]

if you have a junkyard near, just for good measure, replace the IAC valve...I have something even better... a parts car. Sure, I'll take a shot and swap that, thanks for the suggestion. Can you tell me what IAC stands for? I still have to wait until the morning to look it up in the manual because adobe acrobat doesn't work on this computer, it just freezes (I hate WinXP, if it wasn't so time consuming I would go back to W2K and I will eventually) and it would be easier to look up the part in the manual and where it is in the engine if you told me the full name. As you may have realized I'm not that familiar with IC engines.

BTW I wish the PDF manual was searchable (OCR-ed) and not only a scan. It made me look through it, though.

[Slavic]

I want to add that seafoam specifically significantly improved the hesitation and erratic idle within a 100 RPM range, which was much more noticable before applying it, but didn't completely remove the problem and neither did the b12 which was applied after seafoam.

[MarioBurke]

Make sure you dont have any vacuum lines disconnected. usually always the biggest cause of bad idle. especially if you put on a air intake pipe.

[Oldblueaccord]

Putting on the brakes and the idle goes down could mean leak in the brake booster. just unhook your brake lights to test this theory. I have no idea why a 100 amp alt would make your car idle better might even burn up the wires since I dont think there rated that high.

100 rpm differance aint much our cars dont idle well at all

the idle should be set per the sticker on the hood 750 rpm id guess. Try adjusting it and get back to us.


EDit: fast idle is just that for fast idle until the car warms up


wp

[Vanilla Sky]

Idle Air Control... sounds like it might be your problem... and yea, parts cars are great... i have 2...

[thegreatdane]

The idle goes up when you step on the brake, thats perfectly normal.

[Oldblueaccord]

I tested my car tonight when I got home. Full electrical load foot on the brake my idle stayed right on maybe bubled a little. When I released the brake it went up to 1000 rpm for a second then went back to normal. I have a 88 LXi.

Maybe your idle is to low to start with ?


wp

[Vanilla Sky]

if the idle is too low, then his IAC is defective...

[Oldblueaccord]

if the idle is too low, then his IAC is defective...

Something is wrong. I finally read the 4 g altenator swap page to find out what this was all about. I a little behind on what the younger generation is up too lol. I read more about your problem while I was on there.

I would look into maybe raising your idle a little there is a screw on the throttle body to raise it up a little.

The ECU does compensate for loads like steering, amp drain, etc I just not exactly sure how. Id imagine the Eacv which I have said before is a fincky POS so if its bad your not getting any help with your idle under load.

OK quote form the book page 12-13

Elecetronic idle control EACV

When the engine is cold,the A/c is on,the tranny in gear (auto only),the alt is charging, the ECU controls current to the EACV to maintain correct idle speed.


I m still reading.

wp

[Slavic]

Sorry for not replying in a while I was moving and so on.

I cleaned the distributor finally and the contacts were all caked up with stuff. I expected that to get rid of the hesitation (farting, misfiring, whatever it's called) problem since the spark plugs are all new and properly gapped, but it didn't.

Now I'm left with checking the timing which is starting to be a pain because the label on the hood is missing so I can't figure out the stock timing. The shop manual is not helpful as I can't figure out which model my car is (and Haynes manual is utterly useless) My engine code is: A20A3 1221204, tranny: A2Q5 2011708 if someone can figure it out let me know. Even if I figure out the model (KS KX KQ or Other) it still doesn't show my engine A20A3 on the ignition timing page, only A20A2 and A20A4 so I can't figure it out for sure.

AS far as brake rocking the idle I think that is normal. It will surge up by 200-250 RPM after releasing the brake, but all the other electrical loads causing a drop in the idle isn't normal for sure.

I'm still not sure what you mean by idle air control. If it's the "idle control solenoid valve" that is next to the wiper motor and the brake main I swapped that from the parts car (known good) and it made no diference.

The problem persists regardless of where the idle is set 750 - 1100 RPM.

[Oldblueaccord]

Sorry for not replying in a while I was moving and so on.

I cleaned the distributor finally and the contacts were all caked up with stuff. I expected that to get rid of the hesitation (farting, misfiring, whatever it's called) problem since the spark plugs are all new and properly gapped, but it didn't.

Now I'm left with checking the timing which is starting to be a pain because the label on the hood is missing so I can't figure out the stock timing. The shop manual is not helpful as I can't figure out which model my car is (and Haynes manual is utterly useless) My engine code is: A20A3 1221204, tranny: A2Q5 2011708 if someone can figure it out let me know. Even if I figure out the model (KS KX KQ or Other) it still doesn't show my engine A20A3 on the ignition timing page, only A20A2 and A20A4 so I can't figure it out for sure.

AS far as brake rocking the idle I think that is normal. It will surge up by 200-250 RPM after releasing the brake, but all the other electrical loads causing a drop in the idle isn't normal for sure.

I'm still not sure what you mean by idle air control. If it's the "idle control solenoid valve" that is next to the wiper motor and the brake main I swapped that from the parts car (known good) and it made no diference.

The problem persists regardless of where the idle is set 750 - 1100 RPM.


EACV it on the intake manifold behind the fuel rail.