Q: Trouble starting and acceleration bogs down

asked by on September 14, 2016

My truck is having a lot of trouble starting and it bogs down when I accelerate from a stopped position. When it idles, it is a bit higher than normal. Another problem is the shifting which is very hard to shift between gears. I have replaced all of the sensors and also the fuel filter. Would you give me advice on what I should do next to fix my truck's starting problem?

Car is hard to shift Inspection $94.99 - $114.99 Get a Quote
Idle Control Valve Replacement $162.54 - $1028.01 Get a Quote

Hello there, thank you for asking about your 1986 GMC S15. You don’t say whether you have an automatic or manual transmission, so I’m not sure how to help you with your shifting concern. As far as the engine performance problem goes, the first place I would look would be the idle air control valve (IAC). The IAC allows a small amount of air to bypass the throttle to control idle characteristics. If the valve is faulty, the engine may not get enough air and stall. Other potential causes for your concern include, but are not limited to, vacuum leaks or a faulty sensor. There are too many potential causes to list, so I suggest you have your vehicle inspected by a professional. A certified technician from YourMechanic can come to your home or office to diagnose your shifting problem and replace the idle air control valve if necessary.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

How does the coolant temperature gauge work?
Keeping your engine within its normal operating range is of critical importance. If the engine gets too hot, serious damage can result. The engine coolant temperature gauge in the dash of your car gives you the means to track that...
Ignition switch worn
Hello. This is a common problem with 2003 Honda vehicles. The wafers in the ignition switch/cylinder are getting stuck in the cylinder, which is causing it to not turn when the key is in it. The ignition switch cylinder will...
high idle on startup, 2002 Chevrolet Avalanche
Hey there, it looks like you already did a fair amount of work on this. Another thing that you should take a look at is the throttle body. You may have to clean out the throttle body (https://www.yourmechanic.com/services/clean-throttle-body) and get...
Delay in braking, computer doesn't recognize the brakes. 2011 Nissan Leaf
Hello there, this is a very unusual issue with the 2011 Nissan Leaf. The Leaf uses electronically controlled hydraulic brakes. What this means is that the brake pedal, booster, and ABS is all electric. A few different faults could cause...
How to replace thermostat in a 2000 rodeo
Usually the upper radiator hose connects to the thermostat housing. You will want to drain the cooling system first. Then, disconnect the upper radiator hose from the engine side. After that, you will want to remove the bolts from the...
Upon starting, the vehicle has a dry start for about 5 seconds unless it sits overnight.
Hi there. Check the oil pressure sensor and see if its working or sticking. When the oil pressure sensor is sticking or not working correctly, the computer will cut the ignition and fuel off until oil pressure is met and...
Electrical - car battery positive temporarily touched negative - where is the problem?
Reverse polarity, at the battery, in a 12 volt electrical system on a car can cause a variety of effects including damaging the alternator, diodes and the numerous microprocessors on a vehicle such as those in the powertrain control module...
Fiero GT VERY difficult to move shifter from any position. 1986 Pontiac Fiero
Hello - your Fiero uses rather long cables for the shifter linkage (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-shift-selector-cable), and several pivot mechanisms that are potentially very stiff if they have not been cleaned and lubed in recent history. Cold weather also makes cable action stiff...
Engine Died Car wont Start
It is possible that some engine damage may have occurred when this happened. Full Throttle is typically not recommended on many vehicles as it can cause the engine to Red Line. I would recommend having your vehicle inspected by a...

Related articles

Symptoms of a Bad or Failing Air Fuel Ratio Sensor
If you notice a decrease in fuel efficiency or engine power output, as well as a rough idle, you may have to replace any air-fuel ratio sensors.
Symptoms of a Bad or Failing Thermostat
Common signs include the temperature gauge reading being very high or changing erratically, engine overheating, and coolant leaks.
How to Replace an Engine Oil Pump
The The oil pump is the heart of the engine - it pumps vital lubricant and supplies pressure to every moving part. The pump is required to provide 3 to 6 gallons of oil per minute while also maintaining system...