86-E150 Rough engine rumble when accelerating

Reply Subscribe

Thread Tools

Search this Thread

Oct 4, 2004 | 08:24 AM

croman2

Thread Starter

New User

Joined: Apr 2004

Posts: 11

Likes: 0

86-E150 Rough engine rumble when accelerating

Hi,

I have a 86-E150, 170,000 miles, fuel Injected van
that is running rough. it runs fine at idle.
i notice the rumble when i get back on the gas
after slowing down by letting off the gas.
i do a lot town driving so it happens mostly in the
20 - 50 mph range. if i hit the highway or stay on the
gas long enough it does eventually smooth out.

my gas milage is pretty crappy and i did a compression
test the other day. 1 cyliner down around 110 psi and the
others between 130 - 150 psi. i did the test removing one plug
at a time and had the main ignition wire off so it would not start.

time to get the injectors cleaned at a garage?
replace them?
other ideas?

thanks

- Chris

Oct 6, 2004 | 11:39 PM

c96drumm

Laughing Gas

Joined: Mar 2003

Posts: 877

Likes: 1

From: Colorado, U.S.A!

Have you pulled the codes? How about tuneup items like plugs, wires, filters, PCV valve, etc.? Check fuel pressure. BTW, compression should be checked with all the plugs removed at once.

Oct 7, 2004 | 07:33 AM

croman2

Thread Starter

New User

Joined: Apr 2004

Posts: 11

Likes: 0

computer codes are this weekends project.
now that you mention the PCV valve, I have noticed a
small oil leak, which I think is coming from a
valve cover gasket. a valve cover gasket job looks really
unpleasant on this van so I have put off thinking about it.
maybe too much pressure?

how would the PCV cause an engine rumble?

the plugs, wires, air filter, TPS, catalytic coverter, throttle body gasket, O2 sensor,
thermastat and IAC have all been changed or cleaned within the last
2,000 to 10,000 miles.

Oct 7, 2004 | 09:15 PM

c96drumm

Laughing Gas

Joined: Mar 2003

Posts: 877

Likes: 1

From: Colorado, U.S.A!

The PCV probably wouldn't cause a rumble, but when I have a weird problem, I like to make sure all the easy, routine stuff is in good shape just to eliminate those possibilities. Let us know how the codes come out, and good luck!

Oct 12, 2004 | 12:43 PM

croman2

Thread Starter

New User

Joined: Apr 2004

Posts: 11

Likes: 0

I checked the codes, using the lightbulb method, and this is
what i got (i think)

12 - Can't control RPM during high RPM test
13 - Can't control RPM during high RPM test
77 - Operator errror during Dynamic response Check
25 - Knock sensor not detected during dynamic response test KOER

i did the test several times and got the same sequence of flashes.
i think i decoded it right, (it repeated once) 12-13-77-25-12-13-77-25

here is a movie i made of the lightbulb with my digital camera. (sorry the
file is so big)
http://www.mit.edu/~cnr/DSCN0153.MOV

Also, I redid a compression check with all plugs out. all cylinders between 140-150
psi, except one at 110 psi. that one went up to 130 when i dripped some oil in it.

I put in new plugs and it now runs better but i still get a rumble.

Oct 12, 2004 | 08:44 PM

Mustang 5.0

Senior User

Joined: Jan 2004

Posts: 174

Likes: 1

From: Virginia Beach, VA

12 & 13 make me think that the IAC needs leaqning/replacement.

and with that milage, plugs and wires and cap and rotor would be due, unless done reciently.

Oct 12, 2004 | 11:05 PM

c96drumm

Laughing Gas

Joined: Mar 2003

Posts: 877

Likes: 1

From: Colorado, U.S.A!

I agree about checking the IAC. I read your first description of the rumble again and got to wondering if it could be a tranny issue, like the converter not locking up right and creating the rumble while it's trying to lock, or something. I dunno, just something else to check.