Hi Idle rough running under 2k rpm Debuggery

**sakdog** · 08-16-2007, 08:32 AM

Hello all, Its been 2-3 years since on this forum I forgot my old name and password so i started a new account.. I am back in the 3rd gen Accords....I just came across an 88 4d lxi for $350 had a cracked radiator... I tested for blown headgasket...none and i just so happened to have a 3rd gen accord metal radiator laying around from my old 3rd gen days.. So it was a match made in heaven. Heres what happened next:

(this is what it does when not driving) The engine seems to want to idle at around 1250 rpms when warmed up and slightly higher during warm up.. At some times the engine will Idle high, surge up and down between 1000rpms and 1400 rpms for a few seconds and then die Ive had this happen a few times.

While driving
sometimes it acts as if it is just fine and doesnt really act up too bad. But quite often it will have the aforementioned idling problem and the car wants to stay over 2000 rpms. So for instance if im going 35-40 and shift into 4th gear it will start bucking and missing and coughing because the rpms are below 2k it has this kind of behavior whether or not i give it much throttle.. and sometimes even if the rpms are over 2k in gear (moving under load) with more than 30% throttle it will start to cough and buck etc.. at any rate 2000 rpms seems to be a "magic number" because over that it seems to run decent but its annoying because at a stop light ive got to keep my engine speed up to 2k rpm and when taking off in 1st i have to keep the engine reved above that mark while letting out the clutch.

Any pointers.. I know some guys here are very application specific knowledgeable so if someone has had this problem or knows what it might be... i have open ears..

Here is my plan of attack.

Im going to do a basic tune up, The cap looks to be pretty old and the spark plug wires look to be very old... VERY old they are "sumitomo" wires and they have a marking that says 1987.... Scary.. I hope thats not a date mark.. gulp.. plugs look like new and great for a healthy engine. so today The wires, cap and rotor are gonna get changed. This might heal some of the driveability problems but im sure it aint gonna heal the high idle and the surging idle.

The injectors all have a good pulse..
Things that im going to check are.
Fuel filter
IACV ----- Any pointers on checking the IACV
Fuel pressure
distributor
anything else you GURUS can think of..

Thanks in advance

Z.A.C.

**DDRaptor** · 08-16-2007, 10:16 AM

I would offer a bit more help but I have a carbed accord and they are different.

Vaccum lines might have corroded
check the idle control screw too

Best of luck to you.

**bobafett** · 08-16-2007, 11:24 AM

the surging idle might be the fast idle valve which should be the peice on your intake manifold that has coolant lines running into it. I know how to adjust the 86-87 fast idle valve, but i believe the 88-89 unit is different.

**LX-incredible** · 08-16-2007, 12:09 PM

Could be a temp sensor. I had a surging problem and replaced the IAT. It was surging between 500 and 1500 when at idle. Have you checked for vacuum leaks?

**sakdog** · 08-16-2007, 12:17 PM

Thanks guys... Today i ran to the store and picked up the normal tune up garbage... Wires, Cap and Rotor... Boy those components had to have been on that engine from the factory... ..... The rotor was actually TEC brand so it could have been OEM... Sure looked old.... The wires were sumitomo and I am almost willing to be they are the oem wires.. at any rate.. I slapped those new components on and she runs like new.. What a beautiful deal for $350 Now i got to get it painted... Thanks guys