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 Post subject: Engine missing at low RPM. misfire?
PostPosted: Wed Feb 10, 2010 1:24 am 
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I am merely driving my van
I am merely driving my van

Joined: Thu Nov 19, 2009 1:17 pm
Posts: 13
Hi!
Again, more weird problems..
last time I posted a question, it was my steering box + PS pump, then brakes ect...
I don't know if I will see the end of that..

This time, I have some ignition or fuel problem.

During the holidays, I drove down to Florida. Nothing to say, I did the trip from Montreal to Daytona without any snag.
It's when I came back that I started to see some problems. It started on I95 near Jacksonville FL.
I noticed that when I was on cruise control, or at 70 miles-h, everything was fine, but when I was going down hill, or releasing the gas pedal, the engine started to hesitate, to miss.

And it became worst and worst.
If I accelerated quickly, pedal to the floor, the engine was running perfectly, but as soon I was decelerating, the engine was missing fire or something like that.
My worst nightmare was the toll plaza... the stop and go was a big problem.
So to avoid traffic, I drove 30 hours in a row, coming back by night, my girl friend sleeping beside of me...

When I crossed the border, in my country, it became so bad that I was sure that the engine would die in the middle of the highway.
Finaly, the engine died in my driveway!

Two days later, I took the plugs out, replaced them by the original one that I bought at the dealer.
I changed the plug wires.. the truck restarted quickly, but is still missing in the middle range.
On idle, it's perfect, if I floor the pedal, it runs perfectly too, but if I just put a little pressure on the pedal, to hold a fast idle or a 2000 RPM, it runs pretty roughly.
I changed the ignition coil, the fuel filter, cleaned the mass air flow sensor, replaced the cap and rotor.
Checked the fuel pressure, got 55 PSI..so it looks OK to me.
I don't think that the fuel pump is the cause of the problem, otherwise, I will get the symptom at any RPM..right?
I also went to GM and bought a new pick-up coil, (the sensor in T shape mounted under the rotor).
I don't have any codes...The engine check light is OFF.
At the worst condition, on the way back, I noticed that the check light was flashing (missfire detected)
But the light is now OFF.

Any idea?
I'm clueless now! #-o


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Wed Feb 10, 2010 2:51 am 
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Location: Cypress, Tx
what year Van?
sounds like a timing problem to me. On acceleration, the timing is advancing which is getting the timing into the spec range. On deceleration, the timing backs off dropping out of spec. My two cents ...

_________________
'89 Astro, 4.3L, TBI. Minor intake and exhaust mods. Rebuilt 700R4 trans (by me). Corvette servo, 0.5" boost valve, police grade 1-2 accumulator spring (shifts fast and solid). B&M stacked plate trans cooler. Bilstein shocks. Belltech sway bars front and back. New head unit, speakers and subwoofer. Needs paint and a new headliner.

name's Steve
I can't remember all I've forgotten about that....


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Wed Feb 10, 2010 1:27 pm 
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Joined: Sat Dec 02, 2006 8:34 pm
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Location: Orlando, FL
Check the distributor for worn bushings. My 96 Safari would random misfire at will. I changed the distributor after finding the top bushing was worn and allowed the rotor to wobble and that cured it. You might also look at the crankshaft position sensor. \:D/

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1996 Safari SLX Hotair balloon transport vehicle


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Wed Feb 10, 2010 1:39 pm 
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Joined: Mon Sep 29, 2008 3:35 pm
Posts: 692
Location: Victoria B.C.
Give it a vacuum test too.


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Thu Feb 11, 2010 11:23 am 
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I am merely driving my van
I am merely driving my van

Joined: Thu Nov 19, 2009 1:17 pm
Posts: 13
Hi, sorry for the late reply, I was out.
It's a 97 4.3l..
I already replaced the cam position sensor, that's the part under the rotor that looks like a pick up coil on our lawnmower...
But it doesn't change anything.
For the distributor, I don't feel any play in the rotor, weird...
I didn't check for the vaccum, but the timing is mecanic and not electronic on this truck?
Is there any other sensor that I forget that can cause this problem?
Next step, I will strip it apart and sell the parts on eBay! :yawinkle:


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Thu Feb 11, 2010 12:00 pm 
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Location: New Haven, NY
JeffSafari wrote:
I didn't check for the vaccum, but the timing is mecanic and not electronic on this truck?


I am pretty sure there is no vac advance. It is ECM controlled.

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Current rides:
2013 Toyota Tundra DC 4x4
2008 Dodge Nitro 4x4
2005 Nissan Sentra 1.8S Special Edition

Mileage spreadsheet

Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Thu Feb 11, 2010 12:21 pm 
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Dean is correct. All of the timing functions are controlled by the ECU. The sensor inside the distributor is the camshaft position sensor. The crankshaft position sensor is in the lower right side of the timing chain cover. \:D/

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1996 Safari SLX Hotair balloon transport vehicle


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Thu Feb 11, 2010 12:57 pm 
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How is your cat?


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Thu Feb 11, 2010 3:06 pm 
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I am merely driving my van
I am merely driving my van

Joined: Thu Nov 19, 2009 1:17 pm
Posts: 13
I replaced the cam position sensor, for the crankshaft sensor, is it accessible or it's another pain in the ass to remove?

About the catalist converter, is there a way to see if it's the cause? It really sound like a missfire, I don't feel any loose of power and on highway, it runs perfectly.

If it can help, the problem is worst when the engine is cold.
About a week ago, we got a -20 C and it started perfectly when i turned the key...
So obviously, I don't have any problem on idle...


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Thu Feb 11, 2010 3:44 pm 
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I sleep in my van
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Joined: Sun Sep 10, 2006 5:42 am
Posts: 274
Location: British Columbia
To summarize what you have replaced:
Spark plugs
Plug wire set
Distributor cap
Distributor rotor
Ignition coil
Fuel filter
Cam sensor

It appears that all these have been replaced in an attempt to repair the problem without knowing what the fault is. I would suggest that for less than the cost of the parts you have bought, you could have got it scanned & diagnosed.

I could suggest numerous tests to do to try to diagnose but I would require some information that could be gotten with a scan tool to decide which direction to go in.

FYI: Flashing malfunction indicator light = cataylst damaging misfire. In other words, if your cat is not bad yet it will be soon if the problem is not corrected.

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James from B.C.
1992 Safari .060 350 V8
Now upgraded with Vortec heads, GM Performance intake & roller cam
GM Grand Master Techncian - Silver level - 2011 / Bronze level - 2012


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Thu Feb 11, 2010 4:58 pm 
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I plan to be buried in my van

Joined: Mon Jan 07, 2008 2:57 am
Posts: 2165
Location: Elgin, IL
v8famvan wrote:
malfunction indicator light = catalyst damaging misfire

Um, that means the error is currently happening. Steady on means that a code event has occurred and is stored.

Grumpy sets the P0302 (cylinder 2 misfire) at idle and flashes, then at speed the light stays on, when the engine returns to idle the light flashes again. When I clear codes at speed the light stays off, till the engine returns to idle and light flashes again.

Most auto parts will read the codes for free. Start by finding out the code(s).

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Aaron

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1999 Astro (Green the Daily Driver) - 2WD, 3.23, 210k+ miles, FE2 steering
1997 Astro (Grumpy the $250 Rally Van) - AWD, 3.42, 2" lift, 31" tires, 330k+ miles on the orig eng and trans, $30 eBay fuel pump
1980 Kawasaki KE100 (Bessie)
1997 Astro (25% Off) - Defaced parts van
2002 Jeep Liberty (Eugene the Wife's Toy) - 4.10, 4" lift, 31" tires


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Fri Feb 12, 2010 2:20 pm 
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I am merely driving my van
I am merely driving my van

Joined: Thu Nov 19, 2009 1:17 pm
Posts: 13
Ok, you are right! I will bring it to the dealer and if I can get a trouble code. However, everything that I replaced are parts that I had to replace anyway on a good tune-up, so it's no big deal.
I saw the engine light flashing for less than a minute, but not anymore...
I will come back to you guys later next week, after the visit to a dealer.
Thanks for the help!


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Fri Feb 12, 2010 2:48 pm 
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I plan to be buried in my van

Joined: Mon Jan 07, 2008 2:57 am
Posts: 2165
Location: Elgin, IL
Wait, let me show you something.

Codes read at dealer = $$
Codes read at LAPS (Advance, AutoZone, etc) = free

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Aaron

Image

1999 Astro (Green the Daily Driver) - 2WD, 3.23, 210k+ miles, FE2 steering
1997 Astro (Grumpy the $250 Rally Van) - AWD, 3.42, 2" lift, 31" tires, 330k+ miles on the orig eng and trans, $30 eBay fuel pump
1980 Kawasaki KE100 (Bessie)
1997 Astro (25% Off) - Defaced parts van
2002 Jeep Liberty (Eugene the Wife's Toy) - 4.10, 4" lift, 31" tires


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Sat Feb 13, 2010 12:51 am 
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Joined: Fri Sep 22, 2006 2:50 am
Posts: 1378
Location: Cypress, Tx
+1 what Aaron said...
What about the EGR guys? At idle, closed ( or should be ). At high RPM closed, particularly when you stomp on it. in between should be open to varying degrees. Stuck EGR produces said symptoms.

_________________
'89 Astro, 4.3L, TBI. Minor intake and exhaust mods. Rebuilt 700R4 trans (by me). Corvette servo, 0.5" boost valve, police grade 1-2 accumulator spring (shifts fast and solid). B&M stacked plate trans cooler. Bilstein shocks. Belltech sway bars front and back. New head unit, speakers and subwoofer. Needs paint and a new headliner.

name's Steve
I can't remember all I've forgotten about that....


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 Post subject: Re: Engine missing at low RPM. misfire?
PostPosted: Sat Feb 13, 2010 12:52 am 
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I sleep in my van
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Joined: Sat Jun 09, 2007 6:50 am
Posts: 431
Location: Orange County, CA
Autozone will not do it anymore, at least in California. They will only sell you the tool now. They said due to a new law they are not allowed to read codes for people. I say, Lame.

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-James

1987 LT
241,000 miles


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