Rough idle issues, please read.
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Rough idle issues, please read. - 5/20/2007 7:17:46 PM
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94pos
Posts: 32
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1994 S10 Blazer 4.3 W code
Ok, this might be a little long winded but I want to clear up everything I have checked or replaced already before people start spurting out resolutions. On the way home from work the other morning, I had noticed that hitting the gas from a stop there was sort of a delay and then the powerband kicked it. About the time I got home the truck was running extremely rough (only 3 miles), and was running hot (about 250 or so on the gauges), and I almost ran into my garage door backing my truck up because it had no brakes at all.
It's been three days of fighting this truck and this is what has been replaced.
Idle air control valve (warranty)
TPS
MAP Sensor
Ignition Module
Cap and Rotor
AC Delco plugs + accel wires
MSD blaster coil
Oxygen sensor
Now I had a few problems with the laggy starts off red lights a day or two before it finally died, and had intermittent SES lights coming on, but they were never hard codes so my obd1 scanner did not pick anything up. I pulled the round valve (some kind of recirculator) off the top of the motor and cleaned it up. I took the EGR valve off and it appeared to be jammed up with carbon, I cleaned it out but HAVE NOT installed it back yet. I also messed with the timing at the distributor w/ECU hooked up and not hooked up, doesn't seem to make any difference.
What is the round piece on the top of the motor? Is there anyway to test it? The parts store has no idea what it is or how to replace it. I doubt cleaning the EGR is going to help and I dont want to spend $220 on one and have the truck still not want to run right, I am running out of cash this paycheck ugh.
I saw a few posts about the CPI and injector/regulator/nut kit, but mostly I see the problem on 1995's W codes, is it similar with a 1994 W code?
Somebody please give me some advice, I am out of patience and out of money. Thanks!
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RE: Rough idle issues, please read. - 5/20/2007 7:34:46 PM
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94pos
Posts: 32
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forgot to mention truck has NO catalytic converter so this is not part of the problem
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RE: Rough idle issues, please read. - 5/21/2007 5:58:30 AM
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swartlkk
Posts: 14530
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The EGR valve being all carbon'd up could be the reason for the issues you have been having. If you have gotten it cleaned up and verified that there are no vacuum leaks in the diaphragm on the valve itself (I can't remember if its vacuum controlled or electronic like the newer ones), slap a new gasket on it and reinstall it. See how things go.
And all CPI motors are equally susceptible to internal fuel leaks. Some get lucky and never see the problem. Before coming to the conclusion that the spider or fpr is at fault, a fuel pressure and leak down test must be performed. If you determine that there is a leak somewhere in the fuel system, the next thing would be to remove the 'round piece on the top of the motor' (I know the name of the part, but I cannot for the life of me remember it right now). Look down into the plenum and see if there is a pool of fuel on the passenger side of the motor. If there is, then you have an internal fuel leak. Pull off the upper plenum and pressurize the fuel system again. Inspect for the exact location of the leak.
Let us know how those checks go and we can advise further.
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RE: Rough idle issues, please read. - 5/21/2007 11:06:32 AM
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94pos
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Ok, so I cleaned out the EGR really well, it had a little rock of carbon keeping it stuck back ( I guess open), after playing with it it seems to open and close fully, not sure how long this will last though. As far as a vacuum leak, it's electronic on my motor. I found a pinched spark plug wire and replaced all of the wires with accel as well as the cap/rotor.
It's running a lot better but still something is wrong. When it idles it sort of runs a little rougher than normal and sorta spits and sputters, almost like a misfire or backfire...it's strange I can't tell what it is. I have checked over all the plugs and everything I could see for anything thats wrong.
I took it out on the road and drove it, it seems ok, throttle response could be better, but then it shifts from 1st to 2nd and sorta bogs down, not transmission but the motor actually drops rpm and almost dies, then comes back to life but still runs like crap...at this point it pretty much runs like **** until you let it idle for a minute.
I let it idle outside for 45 minutes or so, it would get rough and I would hit the gas for a minute or two and it would clear up.
My friend had said to check the distributor and advance the timing a little but I don't know if this is good advice..? I am going to check in that whole right now to see if I see any fuel leaks.
Thanks!
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RE: Rough idle issues, please read. - 5/21/2007 11:53:58 AM
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swartlkk
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When was the last time you ran some fuel system cleaner through it... I run a large bottle of Chevron w/ Techron through all of my vehicles at every oil change just to keep things cleaned up.
I suppose it is also possible that you have some water in the tank. A red can of Iso Heat will fix that problem.
Both of the above suggestions aren't 'break the bank' items, however, they may not do a thing for your problem aside from rule out those two possibilities.
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RE: Rough idle issues, please read. - 5/21/2007 12:06:07 PM
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94pos
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I put a bottle of this in it last week http://www.autobarn.net/ch05063.html
The problems did not start until a full tank of cheap gas at (wawa)...after half a tank of that (87), I filled it up with 92 since it was running bad. 16 miles later I am coming home from work at it reaches the climax of it's messing up.
I checked inside the (imtv?), aka "round thing on top", and I see no clean spots or any signs of a leak, just lots of carbon everywhere. I will try some of that stuff and some fuel additive and see if its the gas, I just went over everything in the motor again and I still cannot find anything astray.
I tried unplugging the imtv and egr and starting it, no difference. Do you think my egr could actually be broken and cleaning it didnt help anything?
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RE: Rough idle issues, please read. - 5/21/2007 12:06:50 PM
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94pos
Posts: 32
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Oh and where can I get iso heat at?
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RE: Rough idle issues, please read. - 5/21/2007 12:15:01 PM
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swartlkk
Posts: 14530
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Ah yes, that is what it's called! IMTV == Intake Manifold Tuning Valve. Here's some info on the IMTV:
quote:
The IMTV relay is mounted on the firewall and gets its signal from the ECM (Electronic Control Module). It turns on at 3,025-4,650 rpm with a throttle angle of above 36 deg., and off below 2,975 rpm or 34 throttle degrees, or if rpm exceeds 4,650.
Anyway, Iso Heat is available at pretty much any autoparts store and your friendly neighborhood Walmart among many other retailers.
It is possible that the EGR valve is causing all of these issues. If the EGR valve is remaining open, it will result in poor idle quality and depending on how 'open' it is, it can cause a vehicle to stall.
< Message edited by swartlkk -- 5/21/2007 12:17:00 PM >
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RE: Rough idle issues, please read. - 5/21/2007 12:43:58 PM
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swartlkk
Posts: 14530
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The SCFI motors (mid/late '95 change over) do not have an IMTV. In your case, you do have one and that is what we are talking about. The plenum of a CPI motor is split into two different halves, right bank and left bank. The function of the IMTV is to connect those two banks at a certain RPM. What this does is removes the restriction at higher RPM that having the banks separated encurs. With the banks separated, at lower RPM, the torque curve is boosted slightly, however, this hinders high RPM power which is somewhat alleviated by the IMTV opening.
You may be able to check that the EGR valve is, in fact, the cuprit. If you have a small plate of steel and a drill, you can fashion a block off plate to temporarily use to eliminate the EGR valve from the system. This would either rule out the EGR valve as the cause or fix the problem, meaning that the EGR valve is at fault.
Now, before anyone jumps on me about blocking off the EGR valve, this should only be done temporarily as a test. EGR gasses actually serve to reduce NOx emissions by cooling down the cylinder temps. It does so by displacing incoming volitile air with innert exhaust gases which cannot support combustion. This not only serves to reduce the emissions of the vehicle, but the reduction in cylinder temps also extends the life of the exhaust valves. So use this as a test to figure out if your EGR valve is truely at fault before dropping the coin.
*EDIT* - Ah well that's cool. So you don't have to do the whole block off plate idea then. That'll work as well.
< Message edited by swartlkk -- 5/21/2007 12:45:01 PM >
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RE: Rough idle issues, please read. - 5/21/2007 3:18:58 PM
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94pos
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Alright, it's been on for about 2 hours...part of which was me driving around town. First impressions are that it's fixed. I put the new egr in along with some iso-heet and some fuel injector cleaner, wawa has been dispensing watered down gas these past few weeks so I think thats part of it.
Fired it up, a little rough but evened out, drove out of the driveway (about 150ft long) and it ran good..pulled out on the street and as soon as it shifted to 2nd it bogged down but never as bad as it did before and it cleared up after about 3-4 seconds. I drove for roughly 20 miles after that, stop and go, all speeds including up to 70 with NO problems, truck ran great! Turning onto the street I live on, I stopped at the stop sign, then hit the gas to turn and it sorta shuddered for a second and then took off. Aside from those two things it seems to be doing good. I just fired it up after an hours rest, little rough idle but evened out after a few seconds.
Should I be worried? I hope it doesn't persist or get worse.
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RE: Rough idle issues, please read. - 5/23/2007 12:04:22 PM
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94pos
Posts: 32
Joined: 5/20/2007
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Now i'm having a timing issue, the accel cap and rotor came in and I attempted to install it, with no luck. It doesn't want to fit on correctly but when I did get it straight (looking at the clips at the back over the ignition module) and having the holes line up, the truck will not fire. In the middle of messing with a stupid cap for over an hour, I moved the wires around so much to were I forgot where they went (lol). Anyway, putting the regular sorensen cheapy cap on and the truck starts right up but runs as if the timing is off, rough with no power.
Starting from the front right and going around counter-clockwise I have it set like 123456. I am assuming from the drivers side it's 1-3-5 and passenger 2-4-6. So assuming firing order is 612345, I have the wires on there. I have been messing with it for 3+ hours yesterday trying to get the truck to run right. Something must be wrong, any ideas?
EDIT: Forgot to mention but was obvious, in no way shape or form could I get the Accelt cap and rotor to do ANYTHING. Fits like crap and even when it's on there perfect it wont do anything. I have inspected it and everything looks fine.
EDIT 2: Removed all spark plugs and checked to make sure they were all gapped correctly, they were. All were soaked in oil, mainly the driver side and the passenger side just had a little oil. Is this something I should be worried about? I cleaned them off well and started the truck and it's still running rough, no power like timing is off or a vacuum leak. I don't know what to do if it is a timing issue...and I can't find a vacuum leak to save my life. I pulled the vacuum hoses off the back of the intake manifold and plugged it and it seems to run better, but as soon as you hook the hoses back up the motor seems to stall. There is 4 hoses running off of the one vacuum connection, (two tee's), is this normal?
I put accel wires on it yesterday as well as the cap (which is currently awaiting return to advance), I swapped them back out for the 7mm cheapies and it made no difference. Someone please help, my main car is at the body shop because my wife wrecked it so I have to take to train to work my 9-7 night shift.
EDIT 3: Let it warm up. Still ran rough. No CEL. Still a rough run, not a low idle but sorta a put put like it's not enough fuel or timing is off, seems to be firing fine but I really can't tell. I guess I will take it somewhere tommorow and pay out my a$$ for them to tell me what it is.
EDIT 4: still not running right...could the rotor hitting the inside of the cap have thrown the timing off? I think that's the issue.
< Message edited by 94pos -- 5/24/2007 12:19:59 PM >
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RE: Rough idle issues, please read. - 5/25/2007 10:19:59 AM
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94pos
Posts: 32
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Heres an update. Took it to a shop yesterday to have it timed and checked out, they charged me $133.50 just to tell me nothing was wrong with the truck. This guy actually said that. Anyway, on the way there the truck had heated up and mysteriously just stopped shuddering. As soon as I start it this morning it starts it up again. It must be related to the truck being cold.
So it went in to another shop today. Timing was off a little bit, wont tell me what else he fixed just says a lot was messed up and they believe the ECU is messed up. Either way, it wont be ready until at least tuesday so now I have to rent a car for my 1800 mile trip to georgia and back tuesday. What a pain in my ass....i hate my blazer.
< Message edited by 94pos -- 5/25/2007 2:35:47 PM >
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RE: Rough idle issues, please read. - 6/6/2007 3:02:01 PM
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94pos
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So after the shop spent a week not having a clue what the problem was while charging me out the ying yang, I got it back. I have replaced the whole fuel spider kit (thanks to info on here), as well as the ecu and timing gear + chain. problem is still irratic and unpredictable
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RE: Rough idle issues, please read. - 6/10/2007 6:15:20 AM
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swartlkk
Posts: 14530
Joined: 5/1/2005
From: Waterloo, NY
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Have you had the distributor out? If you have, did you check the condition of the gear on the bottom? I have seen a few of these gears crack creating some pretty weird symptoms. Have you verified the base timing? To do this, you need to disable the electronic advance.
While a new fuel filter is cheap enough, I don't normally attribute idle issues with a fuel filter issue. Typically if a filter is restricting the flow, there will be more high rpm issues than at idle simply due to the flow requirements.
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RE: Rough idle issues, please read. - 6/12/2007 4:33:36 PM
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94pos
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Fuel filter is brand new, sorry for leaving that out. Distributor is under a year old, have pulled it out and checked it over, no cracks and the shop set base timing when they had it.
Pulled the upper plenum off today, there is some serious runs in the carbonation on the drivers side by the in/out fuel lines, and a few puddles of fuel. On the drivers side there is no sides of runs of the carbon, it's thoroughly gunked up, but it's also got two small puddles of fuel in there as well.
I went ahead and ordered and AC Delco spider kit and a fuel line nut kit, and picked up the intake gasket at AAP today.
Will update when stuff arrives.
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RE: Rough idle issues, please read. - 6/27/2007 11:01:51 AM
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nemesis_SS
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Did you do anything about the oil on your plugs? (mentioned in the post on the 23rd). If the valve cover and spark plug gaskets are leaking onto the plugs nothing is gonna fire properly - which would by why the power loss/rough idle. You may be ablwe to find out if that is the problem by pulling the plugs out, cleaning them, and then dumping in one of the seal conditioning lubes (theyre allt he same in my experience). Run it for ten minutes and see what happens. Those dont last long though, if it is the problem youll have to change the seals. Course, if oil on the plugs is the problem, it should show in your exaust.
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