1991 Chevrolet C1500 Logo
Posted on Jun 23, 2011
Answered by a Fixya Expert

Trustworthy Expert Solutions

At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.

View Our Top Experts

My Z71 350 skips bad sometimes. i have replaced the coil but it still skips and is getting worse. what does it sound like?

2 Answers

Ben Darden

Level 3:

An expert who has achieved level 3 by getting 1000 points

Superstar:

An expert that got 20 achievements.

All-Star:

An expert that got 10 achievements.

MVP:

An expert that got 5 achievements.

  • Master 984 Answers
  • Posted on Jun 23, 2011
Ben Darden
Master
Level 3:

An expert who has achieved level 3 by getting 1000 points

Superstar:

An expert that got 20 achievements.

All-Star:

An expert that got 10 achievements.

MVP:

An expert that got 5 achievements.

Joined: May 07, 2011
Answers
984
Questions
0
Helped
313639
Points
3004

Hi,

Improve the FixYa.com experience for everyone by voting!

WARNING! I'm sometimes accused of not giving short answers. However, my philosophy is that too much is better than too little.

Still with me?

This is how your problem is researched in my shop. Out of the box, I'd say that you have a problem with the fuel management system. However, there's a good chance that it's something simple and inexpensive like a clogged fuel filter or water in the fuel tank.

My second area of concern would be the manifold pressure sensor which is located under the hood, center, rear engine area, above valve cover, mounted in bracket. However, you must remember that these are nothing more than starting points and not guaranteed solutions at this preliminary stage.

First a little background for your edification. You may be aware of all this but we've never done business before and all assumptions are off the table.

For an engine - make that any engine and irrespective of manufacturer - to run, you need three things to happen inside the engine, compression, fuel and ignition, without any one of these components the engine will not run.

• Compression - Engine compression caused by crankshaft rotation and pistons moving up and down inside the engine block. If the timing belt or timing chain fails it will cause the camshaft to become out of correlation with the crankshaft or allow the camshaft to stop rotating. Either of these conditions will cause the engine to lose compression and sometimes cause internal engine damage.
• Fuel Delivery System - The fuel system includes: fuel pump, fuel injectors, pressure regulator, fuel filter and pressure lines. This system is used to supply fuel under pressure to the fuel injection system, the lack of fuel pressure or volume will cause the fuel delivery system to fail and the engine to stall or not start.
• Ignition Spark Delivery System - The ignition system components include: spark plugs, spark plug wires, distributor (if applicable), crankshaft angle sensor, camshaft angle sensor, ignition coil, ignition module, knock sensor and PCM (powertrain control module). The engine relies on the ignition spark to be delivered to the combustion camber at the correct time. If the ignition spark stops or is delivered at the wrong time the engine will not run or run poorly.


Whenever your engine cranks but does not start, runs rough, staggers, sags or cuts off, follow this Troubleshooting Guide. Some of these steps require a code scanner. They are costly but AutoZone will loan you one for FREE.

Most vehicles operate by the same principle; basic troubleshooting procedures apply to most cars.

• Step 1: Anytime you have a problem with electronically controlled components such as an engine, transmission, ABS brake, or SRS (supplemental restraint system, Air Bag) inspect all fuses using a test light and check the under hood power distribution center and under dash fuse panels. If all fuses test okay continue to the next step.
• Step 2: To check for problems with electronically controlled components such as an engine, transmission, ABS brake, or SRS (supplemental restraint system, Air Bag) and the fuses test okay a trouble code scan - borrowed from AutoZone - is needed to identify any system trouble. Use this easy-to-use simple scanner tool to retrieve trouble codes and see if they relate to the specific problem, like a crank angle sensor failure code. If the trouble code present does not pertain to the immediate problem like an EVAP code ignore it until a later time, after the car is running.


NOTE: Scan the system again after the vehicle is running. The reason is that non-related codes can be detected after the engine is running because sometimes false codes can be triggered by the engine not running. Once the engine is running again the code present might cycle and turn itself off. You might say "if the engine doesn't run shouldn't it have a trouble code?" Sometimes conditions occur that will not be detected by the computer, example: if the fuel pump fails the computer cannot detect the failure, so the engine doesn't start and the computer thinks everything is okay with no codes. If no trouble codes are present proceed to the next step.

If you have trouble using the code scanner or interpreting the codes click on the following link and use my access code (carrepair): Free Automotive Repair information for Users of a Code Scanner www.repairpath.com

All the best

Ben

Anonymous

Level 3:

An expert who has achieved level 3 by getting 1000 points

All-Star:

An expert that got 10 achievements.

MVP:

An expert that got 5 achievements.

Master:

An expert who has achieved Level 3.

  • Master 397 Answers
  • Posted on Jun 23, 2011
Anonymous
Master
Level 3:

An expert who has achieved level 3 by getting 1000 points

All-Star:

An expert that got 10 achievements.

MVP:

An expert that got 5 achievements.

Master:

An expert who has achieved Level 3.

Joined: Jun 21, 2011
Answers
397
Questions
0
Helped
121573
Points
1133

By skips, I assume you mean misses. If it's missing, changing the coil wont solve the problem. Are the spark plugs fresh? What is the condition of the ignition wires? How are the cap and rotor? If they're all good and the problem is getting worse, check the compression on all of the cylinders. You can get an idea of which cylinder(s) are missing by starting the engine cold and letting it run for 20-30 seconds, then feel the exhaust manifold(s) to see which cylinder(s) has a cold manifold that corresponds to it. Normally, if a valve or head gasket lets loose you will get a miss that can become progressively worse and you will get some backfiring associated with it.

Ad

Add Your Answer

×

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

0helpful
1answer

2003 monte carlo 3.4 130,000 skips on start up

I'd suspect a sticking injector--car should have set the check engine light. Read the code(s) to progress further. If the coil pack were a problem, it would not be likely to fix itself. If the codes indicate an injector problem, try an injector cleaner in the fuel--worst case, replace the bad injector. The codes should indicate which cylinder to change the injector.

0helpful
1answer

Runs great but sometimes after a hour starts missing and shuts off.

Not positive but sounds like coil pack. There is a liquid coolant in em and if it gets a crack in it then it over heats easy. So after it gets hot it stops working. Then it cools back down and works right. Just basing this on other cars I have worked on. Some have two wires per coil. When it starts running bad pull one of the wires off and seee if it runs the same or worse. And if it is the coil you should be able to trace down the one that is bad. Just trying to help.
0helpful
1answer

Ruff idle when at idle gets worse when you put in gear

Sounds like a skip, or a cylinder has stopped working. This may be due to no spark (coil pack), no fuel (Injector), or even bad compression (Bad valves, cracked head, or something mechanical.)
Get it checked out.
0helpful
1answer

I have a 93 grand cherokee lerado with the 5.2 engine. the first thing to happen is the ignition coil went all of a sudden while driving. replaced the coil and ran great for two weeks then it started to...

How did you determine bad coil? was it not sparking period? I ask because coils rarely if ever go bad... What is the fuel pressure? Are the injectors firing? Spark plugs fouled?
Other sensors to check: Coolant temp sensor? Manifold air temp or intake air temp sensor? O2...These will change your air/fuel mix at temp if they're bad...
1helpful
2answers

1999 gran marq has new alternater,fuel pump and filter,spark plugs and boots but still skips while idleing and mostly while accelerating,,,getting worse also

I will try to add a few things to check. It sounds like bad plug wires or a coil going out. Sometimes if you water mist the coil and wires with a spray bottle you can see the sparks jump. It will be easier to see in a dark area with the motor running.

The Intake manifolds were changed from metal to plastic to prevent carbon buildup in the EGR passage. This would be under the Metal Airhorn and under the gasket where it attaches to the top of the Intake. There is a groove to clean that carbons up and throws bad codes and interferes with the engine running good. 8 bolts and a $10 gasket and 1Hour of your time to fix it.

You have not mentioned any codes or testing results. Your onboard computer can be checked for free at Autozone or Oreillys. Your "check engine" light should start setting defect codes if your misfires are getting worse. Also, if you can remember a wet plug when you removed your old plugs, that would be a good indicator of a bad wire for that cylinder.

Let me know if you have been fixed.
1helpful
1answer
0helpful
1answer

Engine skipping from idle all the way to highway speed. new plugs

You should replace the wires before you spend money on the coils!
1helpful
1answer

I sprayed water under hood now car jerks

The 4.6 lit motors have individual coil packs. usually, they are not very suceptable to water but... If the check engen light comes on (amber light on the dash) It's probly just skipping. Get some one to put the car in drive and hold the brake. Under load the skip will be worse. Unplug each coil one by one. As they are unpluged,the motor will shake worse. when you unplug one and the skip dosn't get worse, you have found the bad cylender. Odds are it's a coil pack but replace the plug too.
0helpful
1answer

Skipping when gets warmed up

Is the check engine light on? If so get the code it will tell yoou which cylinder if it is a coil. These have 8 coils on them I think and each one can go bad. I just replaced all the coil packs on my moms Lincoln, Everytime I would replace one another would go bad, it had 200,000 miles on the old ones. I ended up just replacing them all, because I didn't want her to get off somewhere and have problems.

If it's not thrown a code it is most probably a vacumn leak/bad plug/bad injecctor.
Not finding what you are looking for?

351 views

Ask a Question

Usually answered in minutes!

Top Chevrolet Experts

ZJ Limited
ZJ Limited

Level 3 Expert

17989 Answers

john h

Level 3 Expert

29494 Answers

Thomas Perkins
Thomas Perkins

Level 3 Expert

15088 Answers

Are you a Chevrolet Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...