Idle, SES, Power-Loss - Please help
Login  | |
|
Idle, SES, Power-Loss - Please help - 3/23/2008 12:19:49 PM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
Long winded here, sorry.
Got a 91 4.3L TBI, just bought it. Replaced the following:
Spark Plugs(Gapped Properly)
Wireset
Rotor
Cap
PCV
TPS
Exhaust from the cat back(Replaced muffler with cherrybomb turbo. Original configuration on the pipe, just upgraded the 2 1/4 pipe to 2 1/2 pipe)
Serp. Belt
All fuses
And when i got it inspected it didn't want to pass, the guy passed it tho, but it looks like maybe my o2 sensor is bad. In general the car runs good, except when at idle, it currently idles at under 600rpm according to the inspection stations computer. Is very rough, but any gas and it runs smoothly. Does seem to be lacking power, of course I haven't had it fixed yet to know for sure, just a feeling.
Trying to stop pouring cash into this for a while so I can enjoy finally enjoy owning a blazer but I need your help. Any ideas where I should go next? I've thought about cleaning the map, maf, and egr but don't know how, found some tutorials but t5hey are for much newer trucks, I will try anyway tomorrow on my day off to make any adjustments to get it done. Any other ideas?
The exhaust repair was to fix holes, only one leak was found before the muffler and that was patched by the muffler shop, it was from the hanger breaking the weld. No other leaks were detected in the system. I would think that the straight through cherrybomb turbo is causing too much of a drop in back pressure, but it idled low and rough before too.
Thanks.
_____________________________
1991 Blazer Tahoe 4DR 2WD
VIN Z 4.3L TBI
|
|
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/23/2008 12:53:59 PM
|
|
|
94blueknight
Posts: 1520
Joined: 12/31/2007
From: Wisconsin
Status: offline
|
how did ur spark plugs look when u did them and when u did ur blazer idle rough when u did the spark plug change? also do u notice worse gas milage and a strong smell of sulfer coming from the exhaust?
_____________________________
CHECK IT OUT its ME!
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/23/2008 6:59:23 PM
|
|
|
swartlkk
Posts: 15304
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
|
No worries on the exhaust. At idle, you don't have an issue from that.
You don't have a MAF sensor.
How does the fuel spray at idle look? Does it form droplets or does it stay in a nice spray pattern?
_____________________________
Kyle-
My Restoration Projects
Please Do Not PM for Tech Help
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/23/2008 11:15:34 PM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
Nice to know about the maf sensor, the fuel spray I haven't looked at that closely but I do remember it being more like a drip than a spray, seemed odd to me.
I don't remember on the plugs, besides the description would suck anyway, so I'll get them out tomorrow, I saved and marked them, and I'll upload a pic of each one and you can tell me. There was nothing deformed about them, just an off color that I don't know about, not white though.
I'm assuming you're gonna say the injectors are dirty/clogged, so how do I cleam them? Can't replace them for a couple of weeks so I hope they can be cleaned. I also did run a bottle of stp injector cleaner through the tank last week, and I have burned through that whole tank already. As for mileage, I haven't driven it steady enough to check mileage, but it's definately under 20 in any kind of driving. Though I did a very corroded exhaust system, couldn't hardly get any air out of the tail pipe, let alone enough to smell, but I'll check that too just to be thorough.
Oh forgot one thing, when I changed the plugs, found two plugs that were far less than handtight, one of those had a wire just hanging on the tip, not actually clipped on, and one of the other wires was a full half inch off it's seated position on the cap. I'll include pics of the cap and rotor contacts as well. It idled better after the plug change, but just as well as it does right now, I've only had the truck for two weeks.
Thanks.
_____________________________
1991 Blazer Tahoe 4DR 2WD
VIN Z 4.3L TBI
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/24/2008 12:16:02 AM
|
|
|
94blueknight
Posts: 1520
Joined: 12/31/2007
From: Wisconsin
Status: offline
|
ok ya rough idle can be caused from a couple of things like the injectors being bad, the fuel lines in the plenum r bad, or the egr valve is clogged (might be a few other problems i dont remember). but ya if ur spark plugs were fouled out on one side or at all then it would be a fuel related problem.
_____________________________
CHECK IT OUT its ME!
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/24/2008 12:45:59 AM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
They weren't fouled out really, I mean the engine wasn't missing at any point before I changed them, just rough, but then again I've never had or heard of a car or truck idling at 530rpm in park, drive maybe but not in park. Everything seems to be about original on this truck, so I've got some work to do with things like clogged egr valves and injectors etc.
I'll have to get my manual out and see if I can find anything that'll help me with my first egr cleaning. But the plugs were just brownish in color, almost like rust, they were also gapped out to like 60 or higher while my manual says the 220 tbi on the 4.3 should be at 35, though I did leave the plugs at a 40 gap as they came, I just made sure each one was gapped the same at 40.
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/24/2008 3:49:43 AM
|
|
|
swartlkk
Posts: 15304
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
|
As far as cleaning the injectors, I would use two bottles (18 gallon treatment size) of Chevron Techron Concentrate Plus in one tank of fuel. Dump the bottles in before you fill up. See if that helps. You also might want to replace your fuel filter.
TBI engines do not have internal fuel lines.
_____________________________
Kyle-
My Restoration Projects
Please Do Not PM for Tech Help
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/24/2008 12:24:46 PM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
Okay, good tip on the filter, it's after market but dunno how old, thanks, and here are the pics. First is a referrence to how I lay out the plugs, left my book at work so no firing order or anything.
http://www.brokesanity.com/blazer/ref001.jpg
Here is the rotor.
http://www.brokesanity.com/blazer/rotor.jpg
The cap.
http://www.brokesanity.com/blazer/cap001.jpg
And this one shows the one that the wire was barely on.
http://www.brokesanity.com/blazer/cap002.jpg
Here is the best I could get of the spray pattern.
http://www.brokesanity.com/blazer/pic005.jpg
And a couple more shots trying to catch it.
http://www.brokesanity.com/blazer/pic002.jpg
http://www.brokesanity.com/blazer/pic003.jpg
http://www.brokesanity.com/blazer/pic004.jpg
Okay, here are the plugs, all labeled.
http://www.brokesanity.com/blazer/all.jpg
http://www.brokesanity.com/blazer/d1.jpg
http://www.brokesanity.com/blazer/d2.jpg
http://www.brokesanity.com/blazer/d3.jpg
http://www.brokesanity.com/blazer/p1.jpg
http://www.brokesanity.com/blazer/p2.jpg
http://www.brokesanity.com/blazer/p3.jpg
And the PCV valve.
http://www.brokesanity.com/blazer/pcv.jpg
The exhaust seems to smell very slightly rich of fuel, also the pattern of the exhaust pulses i more like a miss some where, though the engine doesn't seem to be missing. Today it's messing with me and idling pretty good in park, but in drive while stopped it sucks ass!!! It's an automatic by the way.
Thanks.
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/24/2008 2:27:05 PM
|
|
|
swartlkk
Posts: 15304
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
|
The spray looks ok from what I can tell. The cap and rotor have definitely seen better days.
With the older ignition systems, I definitely would not exceed the recommended spark plug gaps. These systems need a shorter gap due to the lower voltage level used.
Have you checked for a vacuum leak? The TBI base gaskets have problems as they age.
_____________________________
Kyle-
My Restoration Projects
Please Do Not PM for Tech Help
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/24/2008 2:39:25 PM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
About the most that I'm equipped to do as far as vacuum testing is to find a bad line and replace it. I've spent hours checking them all and haven't found any with significant cracking, though I have found one that was not connected and cut too short to reach anything, it's by the master cylender and it has no pressure on it at all. I also found a fitting the right size for that hose in front of the proportioning setup for the brakes, but I think it goes to the windshield washer system and it too has no vacuum on it at all.
Aside from that everything there seems fine. Looks like I'm at a stale mate until I can replace the fuel filter and the o2 sensor. When I first bought it it was showing two codes on ses, 13 and 22 I believe, it was one for the tps and the other for the o2 sensor, changed the tps and it went off for several days, but this weekend it started coming back on for a few seconds at a time.
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/24/2008 5:57:47 PM
|
|
|
swartlkk
Posts: 15304
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
|
Try taking some carb cleaner or an unlit propane torch and spray/flow it around the base of the throttle body just for kicks and giggles. If the idle increases, you have a leak.
_____________________________
Kyle-
My Restoration Projects
Please Do Not PM for Tech Help
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/27/2008 10:51:13 PM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
Still haven't gotten to try that test, but I noticed something else today, when I'm in drive and at a stop, the less pressure I put on the brakes the better the idle is, and if I release the brakes completely from a stop an just let it caost on it's own on flat ground, it idles perfectly, like it now does all the time in park or neutral.
I know just enough about brakes to know vacuum drives them, but I was unable to find any leaking lines anywhere on the motor or brake components. Got any ideas? I'm guessing the leak around the TBI wouldn't do it, but I do know where all that vacuum comes from, so I may be wrong. Any ideas Mr. Admin Sir?
It's also getting really bad mileage I found, 134 miles on almost a tank and a half of gas.
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/28/2008 6:55:34 AM
|
|
|
c0a8l0v6i8n9
Posts: 184
Joined: 1/6/2008
Status: online
|
pull out the vacuum line from the brake booster. Make note what changes in the idle.
_____________________________
1994 4 Door S10 Blazer, 4.3 VIN "W", 99,xxx miles, Xenon Lights, Fog Lights, Driving Lights, Pioneer DEH-3900MP, Infinity Kappa 462.7CFP, Kenwood KFC-1682ie.
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 3/28/2008 7:14:02 AM
|
|
|
swartlkk
Posts: 15304
Joined: 5/1/2005
From: Waterloo, NY
Status: offline
|
Sounds like you have a vacuum or EGR leak somewhere as I stated before. The brake booster does utilize vacuum to supply assistance with applying the brakes, but it should not cause the idle to change significantly when you apply the brakes unless there was a leak somewhere else, reducing the available vacuum in the engine.
But it is also possible that you have a leak in the vacuum booster. Here is the way to test that. Turn off the truck and let it sit for a few minutes. Pull off the check valve from the front of the booster. You should hear a rush of air when you do this. If you do not, you could either have a bad check valve, or a bad booster. If you find that you still have vacuum in the booster with the engine off, I would then do the same test after waiting an hour or so to determine if you have a slow leak.
If you have either no vacuum in the booster or a slow leak, the first thing I would change would be the check valve just because it is cheap. That would be just to rule that out. Then repeat the test. The purpose of the check valve is to not lose the vacuum from the booster while at low vacuum levels during operation or from when you shut the engine off. If you continue to lose vacuum, then you most likely have a booster problem.
As Calvin has said, if you pull the booster vacuum line (check valve and all) with the engine running, you can determine if the booster is good as well. But doing so with the engine running will cause a massive vacuum leak. By covering the end of the check valve with your hand, you can seal the leak temporarily.
_____________________________
Kyle-
My Restoration Projects
Please Do Not PM for Tech Help
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 4/3/2008 11:44:00 AM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
Just an update I thought might mean something, did some calculations and found that for 6 gallons of fuel I ran 100 miles, but because of the tire size being off it actually ran 93.48 miles which gave me a MPG of roughly 15.58 MPG. That's not bad I guess, not a 4 banger but then agains that the point isn't it.
Also, Wife spent all my money on my birthday(Wasn't that nice), so still working on the vacuum leaks, will post back when I know.
Off topic, but one question, what size fuel tank comes in a 91 4.3 TBI 2wd w/Tahoe package? My Book doesn't say.
_____________________________
1991 Blazer Tahoe 4DR 2WD
VIN Z 4.3L TBI
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 4/3/2008 4:46:18 PM
|
|
|
94blueknight
Posts: 1520
Joined: 12/31/2007
From: Wisconsin
Status: offline
|
i have a 94 s10 blazer tahoe 4 door and i have a 18 gal tank and just did my mpg calculations and i am gettin 15.37 miles per gallon on avg (i did this over an entire tank of fuel and went about 270 mi)
another way to check the size of ur tank is run ur gas down to E and then fill it all the way up
_____________________________
CHECK IT OUT its ME!
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 4/3/2008 5:41:54 PM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
Yeah well get this, I put in 6 gallons after running out of gas, well it would start and run but going anywhere caused it to die, and then it happened again yesterday at the end of that 6 gallons, so my calculations will be off by roughly 2-4 mpg since i had anywhere from 5 to 7 gallons used. It's frustrating though, started running out of gas the second time anytime i hit the brakes, or rather anytime i wasn't on the gas, it seems the fuel running to the front of the tank did the trick and I was having to restart on the go until i got a few blocks away to the station, but the gauge read a 1/4 right before that started happening and then by the time it was done, about 10 minutes and 2 miles later, it was almost steadily under an 1/8 of a tank.
I just can't seem to figure this truck out. I'm trying to keep it over a 1/4 thanks to a thread about the fuel pump getting hot, but still getting used to having to put gas in every few days. I never fill up tho either, always between 1/2 and 3/4.
That 6 gallons took it from a 1/4 to 3/4 of a tank by the way, so one of three things is wrong, the tank size being 18 gal, the gas pump telling me i put in 6 gal, or the guage reading that i had 3/4 tank of gas.
|
|
|
|
|
RE: Idle, SES, Power-Loss - Please help - 4/11/2008 12:21:55 AM
|
|
|
Doran
Posts: 19
Joined: 3/23/2008
From: Bedford, Tx
Status: offline
|
Alright, sorry for the long delay. Got an o2 sensor and some carb cleaner today, though didn't use the carb cleaner yet, or the can of seafoam I got.
I did buy a Bosch sensor, but I know what's wrong with that brand, still trying to figure out what's wrong right now so any improvement is enough, I'll get ac delco later in a few months. The truck idles MUCH better and in general runs better, so it looks like the os sensor was the problem, drove it for a while but will find out tomorrow on a longer drive in heat if the cel comes on again, it didn't tonight.
I will also check the base of the tbi for leaks, and I'm wondering about the seafoam stuff. Says it treats up to 10 qts. of oil for one can, so should I use the whole can or just half of it since the truck only holds 5 qts.? And yes, I am going to put it in the oil first, already got my second bottle of injector cleaner over four or five tanks in the gas right now, actually it's octane boost this time, same difference though. Anything you know that I should know about it? Also, just ahd the oil changed less than 300 miles ago, so don't wanna do it again if I don't have to, but after putting the seafoam in don't I have to fairly soon afterward?
And still kind of on topic, found a wire that is unhooked todaym, it is tied in with the main harness on the firewall behind the tbi, the wire appears to be black or some dark color and has a single terminal on the end with a rectangular pastic housing on it. I couldn't find anything to hook it to, do you have any ideas or would a picture of it be more helpful?
Thanks
_____________________________
1991 Blazer Tahoe 4DR 2WD
VIN Z 4.3L TBI
|
|
|
|
Blazer Forum .com is not affiliated with or endorsed by Chevrolet Motors Division or General Motors.
|
Printable Version
