I got a 99 tahoe 5.7 vortec with multiple misfires under load/accelerating. So far Ive replaced; plugs, wires, cap n rotor, coil, egr valve, fuel filter, o2 sensors. Tested; vacuum, fuel pressure, OBD 2 scan. All in which came back ok/no codes. It runs great with the new wires and stuff, but still chugs and sputters when I accelerate or under load! WTF should I do next?...
Posted by KYLE KYLE on
this is one of those situations that a professional diag would of saved you alot of money. Its possible you just got bad gas and your injectors are partially clogged. An 02 sensor would not give multible misfires. EGR would only misfire at idle if stuck partially open since its suppose to be open cruising. Fuel filter would give you a starvation issue but if the misfires happens at idle then the filter most likley is ok.
Data from a professional data scanner will store the conditions when the misfire occurs. Also for a chevy each cylinder will have a misfire counter and one can see the misfire happening as it happens. If its idling and misfiring and gets better as you rev it up most likely you have clogged injectors or a intake vacuum leak. You can test for a intake leak by spraying the intake area with water(idle will faulter if it draws water in), or use brake cleaner (idle will raise when fluid gets drawn in).
If no leaks are found I would do an injection service or at least add two bottles of techron to a full tank, drve till half a tank then top off again.
Also if the catalytic converter is clogged the backpressure could cause all sorts of misfire issues. Removing the two upfront 02 sensors and driving will indicate the exhaust is clogged or not. We put a pressure sensor in place of the 02 sensor. If the pressure is above 5psi this would indicate some blockage. It should be below 3psi at 2000 rpm. Also if you have K/N filter the oil from it will coat the maf sensor wires in time,, (always). You can remove the sensor and spray the wires with brake cleaner to clean. DO NOT touch them. They can be brittle. Look at the wires for color. They should be shiny silver. If its coated the PCM will not see the air volume or accurately see the air temperature. Without this information the PCM will not add enough fuel which will create a misfire.
Posted on Jul 07, 2010
99 Tahoe with 88,000 miles on it. Replaced Master Cyl, front calipers, both rear wheel cylinders, both front brake hoses and rear brake hose.
Also replaced the front brake pads and rotors as well as rear shoes and all drum brake hardware. Brake fluid was extremely dirty. Bled the brakes forever and cannot get a firm pedal and constant air from the front bleed screws. Rear is OK.
Original problem was the left rear drum brake would lock up initially until the brakes warmed up...and since I bought this truck (74,000 miles) it has had a very soft brake pedal. Brakes work OK but the pedal is very soft with excessive travel. No brake or ABS warning lights.
Posted by william... on
Try having the dealer flush and bleed your system. It is very hard to bleed ABS systems yourself and have safe brakes that still work afterward. Bleeding non-ABS brakes yourself is easy not the same for ABS brakes. Valving, sensors and what-not require a tech and the correct equipment in my opinion. You do it wrong and you could ruin your ABS system. Do that and see if they firm up. I replaced my brake shoes/pads at the same time all new everything in back, drums/springs everything and new rotors up front. then I had the chevy dealer flush, refill and bleed system. Stiffer pedal and brakes work better. Keep in mind the brakes on 99 Tahoes are inaedequate, require new rotors often, heat up and fade/glaze pads regularly. I replace my pads long before they wear down because they glaze up and start fading early. I'll rough em up once maybe, next time, new ones. Every two brake jobs, new rotors for me. Just how it is. They will stiffen a bit and work better but they will never be awesome brakes. Just how it is on 99 and earlier Tahoes. Hope it helps. Very important to bleed correctly though. I'll bleed my 83 Toyota 4x4 myself but not the Tahoe.
Posted on Jan 30, 2010
i need the specs to to set the roller lifters on my tahoe.
Posted by dananddoro... on
Crank the engine until the mark on the damper aligns with the TDC mark on the timing tab and the engine is in #1 firing position.
To adjust a valve back off the adjusting nut until lash is felt at the pushrod. Tighten the nut until all lash is removed. This can be determined by rotating the pushrods with your fngers. When all lash is removed the pushrod will stop rotating. When all play is removed rotate the nut one full turn.
With the engine in #1 firing position the following valves can be adjusted:
Crank engine one full revolution - The following valves can now be adjusted:
Posted on Jul 25, 2009
how much should you pay for replacing a fuel pump on 1999 chevy tahoe
Posted by ewarte on
Check this web site for auto repair estimates. Your fuel pump is inside the fuel tank. In my area, the job would run $400-600 at a dealer, $200 or so less at an independent garage, for the pump in the rear tank. If you have a tank on the left side, it runs about $100 more. The site will also have listings for independent garages in your area.
Posted on Feb 05, 2009
My 1999 Chevy Tahoe wont start unless i spray starting fluid into the air intake but once it starts it runs fine, The fuel filter is brand new in it too, if it is the fuel pump how much will it cost me?
Posted by Trevorjd12... on
It is not a fuel pump problem.
It a cold start valve problem. It didn't open. There are 2 things to check.
1- The cooling thermal sensor is not sending the proper signal to the ECU to turn on the cold start valve.
2- The bad solenoid inside the cold start valve causing it not operational.
Case 1 you can easily replace the thermal sensor.
Case 2 checking this requires professional skill to confirm if there is a signal at the valve during the start.
Posted on Aug 04, 2010
1999 2dr chevy tahoe security light flashes truck won't start
Posted by kenneth... on
The security light is a visual indication that something in the car's antitheft system is failing. In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM. (Theft Deterrent Module) The TDM is what tells your computer that the correct key is being used and that it is "OK" to allow the vehicle to start and run. These 3 parts must be in CONSTANT communication. If the key is in the ignition, then these parts are sending important signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, (normally due to a failing/broken part) the car goes into antitheft mode. The car misinterperates this and thinks its being stolen or hotwired because it is NOT getting that signal from YOUR specific key. There is where the security light turns on and shuts down your vehicle. So basically, if that light is on, your system has some sort of failing part. This can start as an intermittent "no start", to your vehicle not running for days at a time, to the vehicle NEVER starting again. The problem is electrical and computer based, so don't count on an easy reset button, or the problem fixing itself. The hard part is isolating which part is the problem. You can spend a thousand dollars through a mechanic very easily. I have had great luck with bypassing the entire system. This way the problem will never return. It actually CAN'T ever return because it is eliminated. This can also be done yourself at a much cheaper cost. Read through this link very carefully. You'll find alot of information and pictures, along with ways to help you fix this.
Posted on Jun 26, 2012
is the switch internal or external
Posted by darrellsca... on
P1810....ATF pressure manual valve position switch malfunction. I think it is external. but i could find little information on this particular code. it is probably attached on the transmission itself. it should have a vacuum plug attached.
Posted on Feb 10, 2009
Is there anything special I need or any tricks ?
Posted by t double on
Escalade, Suburban, Tahoe, Yukon, Denali, Denali XL, Yukon XL, 1999 – 2005
Removal & Installation
4.8L, 5.3L And 6.0L Engines
CAUTION Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures.
Posted on Nov 07, 2008
1999 5.7 2 pc intake
Posted by RANDY... on
Apply sealer to the lower intake manifold bolts prior to installation. On the 5.0L and 5.7L engines, install the bolts and torque in sequence as follows:
Step 1: 71 inch lbs. (8 Nm).
Step 2: 106 inch lbs. (12 Nm).
Step 3: 11 ft. lbs. (15 Nm).
Fig. Lower intake manifold bolt tightening sequence-5.0L and 5.7L engines / zoom image link here
Upper intake manifold mounting bolts/studs, torque in a crisscross pattern as follows:
Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.
Thank you for using FixYa, have a nice day and Merry X-mas.
Posted on Dec 23, 2011
Tahoe will not start, changed the following: cam shaft positioner, O2 sensors, air flow sensor, battery, distributor, plugs are showing yellow spark, these plugs are spit fire plugs. At wits end.
Posted by traveling6... on
check the crank sensor. no signal from the crank sensor causes a no spark condition. best way to check is to put a scanner on and check for rpms.
the crank sensor is differnt from the cam sensor
Posted on Apr 26, 2009
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