Have missfire mainly at idle scanner said misfire cylinder 4. I put plugs,plugwires , button and cap , map senser , coil , miss ant near as bad but still miss mainly at idle but on rd it flys

Asked by Apr 02, 2017 at 11:44 PM about the 1999 Chevrolet Blazer 2 Door LS 4WD

Question type: Maintenance & Repair

Miss at idle runs wide open good on rd maybe
small miss

21 Answers

18,605

Doe it have a fuel injector dedicated for that cylinder, if so it may need cleaning or replaced or check its wiring harness.

1 of 1 people found this helpful.

I'll check I thank 99 has that spider injectors but thanks alot. Pull cap off and the button was about on cylinder 4 so I pulled stribter but my shaff didn't have the factor white line on shaft to line up with notch on bottom of gear but with number one up I lined notch up with button on six that befoul it fell in turned cap towards front of motor and it ended up dead on help a good bit but still has same miss just lighter

18,605

If its spider then it has a injector for each cylinder, I would clean it or use injector cleaner in fuel and also test with multimeter it and its wiring just to rule out any issue from a electric standpoint.

Ya what I can tell one injectors plug between cylinders 6. And 4

Ok I checked injectors good that I talked to man I bought it from he said he pulled a wire out of plug and just stuck it back in there and its on the tps sensor would that create a misfire on cylinder 4

18,605

The TPS provides the most direct signal to the fuel injection system. The lean misfire is another common reason for an engine "miss"—this is due to an imbalanced air/fuel ratio (too much air/too little fuel). It can be soldered in place or grab a connector for it at junk-yard or on the net, (I think rockauto.com has them). Common signs include lacking power when accelerating, rough or slow idle, stalling, inability to shift up, and the Check Engine Light coming on. In most cases, the Check Engine Light is illuminated if a TPS failure is detected, a “limp home” mode of operation with reduced power if a failure is detected. So after the connector fix clear the code (removing the negative battery cable for 1 minutes clears the codes set on the computer). Also Go Back and use some Dielectric grease(bulb grease) on the spark plug wire boots both ends. (Can use a small knife or tooth pick to add this around the inside of end boots/caps on the rubber to decrease misfiring, Also can use on all electrical connection/connectors over the entire car). Make sure all plug wire are not arching on anything or if they can be routed around or over metal/each other then do so and keep them separated. The cheaper wires have little insulation You can but vacuum rubber hose large enough to wrap where they cross each other or metal (cut a length long enough for that area and then slice down the hose lengthwise, open up one end over wire and push it on the rest of the way.) If code continues to set start checking for other breaks in wires(may not see as insulation is not broken too). Check that cylinder for low compression.

18,605

Common causes of a mechanical misfire are worn piston rings, valves, cylinder walls, or lobes on a camshaft; a leaking head gasket or intake manifold gasket; damaged or broken rocker arms; defective fuel injectors (and/or the electronics that control them); and a slipped or incorrectly-installed timing belt or timing chain. Generally, this type of misfire has more of a "thumping" feel to it. It is usually noticeable regardless of engine speed; in fact, it may even intensify as the engine speed increases.

18,605

The lean misfire is another common reason for an engine "miss"—this is due to an imbalanced air/fuel ratio (too much air/too little fuel). Since an engine needs a richer (more fuel) mixture for a smooth idle, this problem may be more noticeable when the vehicle is idling. The lean misfire may decrease or disappear as the engine speed increases because the efficiency of the volumetric flow into the combustion chambers increases dramatically. This is one reason why a vehicle gets better mileage on the freeway than in the city. An EGR valve that is stuck open, a leaking Intake Manifold Gasket, a defective Mass Air Flow Sensor, a weak or failing fuel pump, or a plugged fuel filter are some of the many causes for a lean misfire.

Ok thank you its for sure lean misfire cause its at a idle when you take it up rd it runs good stiff fuel pedal Tran shift hard check engine light flashes so I going to test that tps in morning

18,605

sounds good.

Well buddy of mine has a 99 pickup just like mine checked that wire it was good so we went to pulling and supping parts egr .tps some Idk what they are still not help so I got a wild hair and pulled number 4 plug its dead firing a yellow spark so took his wire it seamed fine but still light light miss but discovered the other evening. A couple blades broke off fan so out of balance might seam like miss when it idle sounds like a v8 cam up so it new wires this evening after work and compression test any pin pointer is be thankful

Ok thank you its for sure lean misfire cause its at a idle when you take it up rd it runs good stiff fuel pedal Tran shift hard check engine light flashes so I going to test that tps in morning

Sorry I for got to summit my last one until now did compression test today and they all around 170 175psi

18,605

Yea 170 is fine, guess you gona put a new blade on since so many blades are missing.

Ya sure am picked it up this evening but when I did compression on it the number 4 cylinder plug looks new fress out of box that the 2nd new plug in it checked plug fire and slight yellow ark so tried another wire good blue ark so took new wires back and bought the very best the had which are 8mm but my old ones 7mm but wife went to advance auto which in not crazy about them did all that and still misfire in cylinder 4 code in no expert I can fix about anything once I know where to go but finding it is my trouble but a good at but friend of mine checked injectors for me when I first talked to you call and said good but I've did some searching and thank I'm going to check them myself thank you so much anything else you thank of would be appreciated

18,605

If you have not yet I would test that TPS.

When the buddy of mine had his pickup here we swapped out Egr valve tps and he did a couple others when I was going still there so where number 4 plug still looks new im going to check the injectors. Myself vie read up a saved on how to check them my wife said when they checked them befoul the wasn't about twenty mins I thank they did check maybe looked would be all

18,605

Since its still down best to recheck it.

I have another question for you if you don't mind on that blazer good looking blazer got it few hundred dollars new I was going to have to put money in it on right side done put axle & ball joints left side done put wheel barring & ball joints wish I would have just put the other axle & barring in it done put idler arm on it pitman and rods have some play I won't to all new in them some people say just do the too bad ones 200000 on it the ball joints was factory still riveted in just going to use for work car but I like it right might be to pickey

18,605

Well I have a 92 Blazer and know one day it will need new suspension parts, But did 4-5 years ago have one lower ball joint start to make a pop every now and then. The others were fine and still are so I found a whole lower control are used at a junk yard that had the same wear as the others on the front and installed it. So I understand replacing what needs it, The problem occurs when one is new and the other side is old, One was worn too much had to be replaced but going to a new one will or can cause the weaker ones to give out, that is why I opted to go look for and find a control are with wear the same as all the others. As far as bearings go I fi put new on one side (not front to back) I do the same on the other side, Same with brake pads/shoes/disc/drums/wheel cylinders/cv axles ect. If its a work truck and you can keep an eye on those and replace as needed or find a weekend or a few days on a holiday pull those and replace with new one is fine, the bearing is the most likely to complain about it sooner that later. Since you already had it apart, how did the bearing feel was it still tight? Must say I always recommend changing the bearings/seals out if doing axles, it has a way of causing the old bearings to go out faster, so keep that in mind and when you have a few days get-ur-done.

Ok thank you for you oppion out of every thing the idler arm was bad with play changed it but still when jack one side or other up you can get play in tire the left to right bearing good tight tie rods has no play the local tire and alignment shop said they put it on suspension lift and let me know what it needs for free I thank steering box has play and number 4 injector was not working you was right on first time so ill get them here soon but thanks

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