Chevy

Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP

Ask an Expert,
Get an Answer ASAP!

2004 impala 3.8 supervharged. Wiil crank over but not run.

Customer Question
2004 impala 3.8 supervharged...

2004 impala 3.8 supervharged. Wiil crank over but not run. If you hold it part throttle while cranking it will start but acts like it flooding over & misfiring, let off the throttle & dies. Every once in a great while, it will crank & idle perfectly but as soon as you rev it it goes to running bad & dies. No security light & no codes on scanner.

Mechanic's Assistant: Does the light flash, blink or stay solid? Have you tried to reset the security system?

With the ignition in the on position, the light is solid, when the car does run, it is not on at all, I have done the relearn procedure also.

Mechanic's Assistant: Are you fixing your Impala yourself? What have you tried so far?

Yes, removed & replaced the fuel filter, I can hear the fuel pump come on. Replaced the battery.

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

I think thats it.

Submitted: 2 months ago.Category: Chevy
Show More
Show Less
Ask Your Own Chevy Question
Answered in 29 minutes by:
5/28/2018
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago
Ivan Alvarez
Category: Chevy
Satisfied Customers: 210
Experience: lead technician at Performance Tire and Automotive
Verified

Welcome to just answer. Does your scanner show live data?

Ask Your Own Chevy Question
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

What are the values for the mass air flow sensor (maf) when you get it to run?

Ask Your Own Chevy Question
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

A​lso look at fuel trim values and let me know where they are at. on both the short and long term trims.

Ask Your Own Chevy Question
Customer reply replied 2 months ago
12.4 inHg
0.8 lb/ min
Customer reply replied 2 months ago
Not sure what you mean by fuel trim, I don’t see that in my data
Customer reply replied 2 months ago
STFT=-25.0
LTFT=-14.8
Customer reply replied 2 months ago
Sorry MAF=0.8 lb/min
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

W​hat you sent is the fuel trim data. It looks like its trying to take fuel away. Have you tried disconnecting the maf sensor to see how it runs?

Ask Your Own Chevy Question
Customer reply replied 2 months ago
it has no change
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

Have you checked fuel pressure with a gauge?

Ask Your Own Chevy Question
Customer reply replied 2 months ago
Not yet.
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

G​et fuel pressure readings when you can. With car running and when off. See how fast pressure drops when off. its possible you have one or multiple leaking injectors.

Ask Your Own Chevy Question
Customer reply replied 2 months ago
Why is it that every once in awhile it will idle perfectly and then suddenly start running bad and die. Leaking injectors either leak or they don’t right? If fuel pump is bad, will it make pressure at times and not have pressure at times?
Customer reply replied 2 months ago
Idling has 48 psi.
Customer reply replied 2 months ago
Now idling MAF shows 0.6 lb/min
Customer reply replied 2 months ago
Fuel pressure does not fall off when it dies
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

Fuel injectors can intermittently stay stuck open. Just have to rule things out. For the fuel trims to be so negative you are right that its flooding out. Its running too rich. What does the coolant temp sensor show when running?

Ask Your Own Chevy Question
Customer reply replied 2 months ago
196
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

Does your scanner give you misfire data? If so what cylinders show misfires?

Ask Your Own Chevy Question
Customer reply replied 2 months ago
It does show me that
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

Check to see what cylinders show a misfire.

Ask Your Own Chevy Question
Customer reply replied 2 months ago
Sorry, meant to type it does not show me that
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

Oh ok. Another possibility is the ignition system. If its not getting good spark to plugs it wont burn the fuel and that would cause negative fuel trims like you have. May be coils or ignition module. So since your scanner doesn't show that data you can someone keep the car running while you pull off wires from the coils one by one to see if there is good spark and at the same time you should notice a difference on how the engine runs. The spark should jump at least an inch. Hold the wire close to the coil tower and it should jump to wire from coil. Dont hold it so close to the boot because it can shock you.

Ask Your Own Chevy Question
Customer reply replied 2 months ago
Seems to have good fire.
Customer reply replied 2 months ago
Any other ideas?
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

Create a large vacuum leak like the brake booster hose. Control the vacuum with your finger and see if you can get the car to run better.

Ask Your Own Chevy Question
Customer reply replied 2 months ago
Ok. I’ll give it a try tomorrow and let you know. Thanks
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

Ok.

Ask Your Own Chevy Question
Customer reply replied 2 months ago
Creating a vacuum did not help.
Customer reply replied 2 months ago
Update...was unplugging the wrong sensor, was unplugging the IAT, i'm a dummy, unplugged the MAF & it ran, plugged it back up while it was running & it died & would not restart until I unplugged the MAF & it started, Will purchase one tomorrow & see if that fixes it.
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago
Ok. Sounds good.
Ask Your Own Chevy Question
Chevy Mechanic: Ivan Alvarez,
 replied 2 months ago

Any new info?

Ask Your Own Chevy Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a chevy mechanicLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Ivan Alvarez Your Own Question
Ivan Alvarez
Ivan Alvarez
Ivan Alvarez
Category: Chevy
Satisfied Customers: 210
210 Satisfied Customers
Experience: lead technician at Performance Tire and Automotive

Ivan Alvarez is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money.

Todd LRochester NY

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

GM Tech (Cam)

GM Tech (Cam)

Chevy Technician

15,756 satisfied customers

GM Grand Master Technician 2007. 14 years experience.

Gary

Gary

Chevy Technician

9,642 satisfied customers

15 years GM master tech

Tim&#039;s Auto Repair

Tim's Auto Repair

mechanic

8,884 satisfied customers

Have owned a repair shop for 25 yrs.

Dave Nova

Dave Nova

Chevrolet Technician

7,092 satisfied customers

ASE Master Certification. GM World Class Certification

John

John

Master A.S.E Automotive technician

4,071 satisfied customers

A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician

Don - Mo Lurch

Don - Mo Lurch

Auto Mech / Electronics

2,953 satisfied customers

Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.

Ron Z.

Ron Z.

- Chevy Tech -

2,836 satisfied customers

18+yrs experience. State Inspector and Chevy Diagnostics

< Previous | Next >

Related Chevy Questions
I have a 2013 Chevy Silverado. It had sometimes run rough
I have a 2013 Chevy Silverado. It had sometimes run rough and sometimes starts out smooth and then gets rough. I have switched out the spark plugs and wires, the foot pedal, and throttle body. After a… read more
GM Tech (Cam)
GM Tech (Cam)
Chevy Technician
Vocational, Technical or Trade Scho
15,756 satisfied customers
I have a 2003 chevy impala that dies as soon as the fuel
I have a 2003 chevy impala that dies as soon as the fuel from the inital pump push is gone, it is a brand new pump just installed … read more
Tim&#039;s Auto Repair
Tim's Auto Repair
mechanic
High School or GED
8,884 satisfied customers
Started with water leaking through my windshield. did
started with water leaking through my windshield. did security reset, still have flashing security light. car sometimes starts then dies, then some times just crankes. … read more
rpmdiag
rpmdiag
High school
7,883 satisfied customers
I tried the pass lock 30 minute procedure now it will not
I tried the pass lock 30 minute procedure now it will not turn over, no instrument cluster is working ect.… read more
David Craig
David Craig
OWNER/MECHANIC
Associates
5,907 satisfied customers
I have an 2003 Chevy S-10 4.3L. The owner had lost the
I have an 2003 Chevy S-10 4.3L. The owner had lost the ignition key so we replaced the ignition lock. It cranks, starts and then shuts off. Scanned for codes and found only the MAP sensor was at fault… read more
Jerry Newton
Jerry Newton
Vocational, Technical or Trade Scho
2,066 satisfied customers
I have a 2002 impala. starts with spray in air intake. it is
i have a 2002 impala. starts with spray in air intake. it is getting fuel at fuel rail under pressure. none of the injectors fire. have had new rockys security bypass installed and it ran fine for a w… read more
Tool Hut
Tool Hut
Owner
519 satisfied customers
04 IMPALA 3.8 HAS SPARK. NEW CMP, ICM, CKP, AND FUEL PRESSURE,
04 IMPALA 3.8 HAS SPARK. NEW CMP, ICM, CKP, AND FUEL PRESSURE, AND POWER TO INJETORS BUT NO PULSE. RAN CONTINUITY TEST ON HARNESS FOR CKP,CMP,ICM AND PASSED.… read more
GM Tech (Cam)
GM Tech (Cam)
Chevy Technician
Vocational, Technical or Trade Scho
15,756 satisfied customers
Chevrolet Silverado 1500 Classic LT: silverado 2003 with 5,3l
silverado 2003 with 5,3l one night quitted on the highway towed home...changed fuel pump and filter...and still does the same...checked fuel pressure at rail and ok....No codes...changed crank positio… read more
Dan
Dan
Automotive Technician
Vocational, Technical or Trade Scho
25 satisfied customers
Chevrolet Blazer (Mid Size): I am working on 1998 s10 blazer
I am working on 1998 s10 blazer 4.3. it sat for 1 year with dead battery. prior to it setting the entire steer column was changed and installer maybe had bad or better advice than myself on relearning… read more
Chris (aka - Moose)
Chris (aka - Moose)
Vocational, Technical or Trade Scho
108 satisfied customers
Chevrolet Impala LS: 05 Impala Ls changed selenoids in trany,,,
05 Impala Ls changed selenoids in trany,,, car cranks no run,,,, security light flash,,, did relearn still no run,,,, did bypass of passlock with resistor security light stopped flashing for awhile,,,… read more
Alex M
Alex M
Automotive Technician
Diplom
858 satisfied customers
Chevy implala: having no crank on my 01 impala 3.8 verified
having no crank on my 01 impala 3.8 verified no signal from pcm (crank fuse in dash fuse box) understood most likely ignition switch issue bu just install new switch still no crank… read more
Eric
Eric
GM service dept Shop Foreman/Lead Tech
High School or GED
615 satisfied customers
2001 impala: security light..car died.replaced..new ignition..new one
2001 impala 3.8 engine security light on, and car died. replaced ignition cylinder with passlock and keys. could not get the computer to relearn the new ignition,so i put old key switch back in, start… read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,642 satisfied customers
2004 Chevy: cranking..without starting..the injectors..ground
i have a 2004 Chevy impala.. the car is just cranking without starting.. we checked the powers and grounds to the injectors the power is good but not getting any ground.… read more
David H
David H
Vocational, Technical or Trade Scho
2,413 satisfied customers
Chevrolet Aveo Crankshaft Relearn Procedure - Daewoo Engine
I recently replaced the engine in a 2004 Chevrolet Aveo with a used engine from a 2007 Pontiac Wave. The original engine had suffered a timing belt failure damaging all 16 valves and all 4 pistons. Th… read more
Triston
Triston
High School or GED
1,134 satisfied customers
Chevrolet Impala 2004. 105,000 miles. Hard to start after
Chevrolet Impala 2004. 105,000 miles. Hard to start after warming up. Diagnostic tools reading "Bank 1 Running Rich." I have replaces the Oxygen sensor that is on the manifold. It runs great when star… read more
carguyjosh
carguyjosh
Associate Degree
1,120 satisfied customers
2000 impala: stater relay out jumper the starter..fuel pump..crank
i have a 2000 impala 3.8 turn the key nothing happens, pull stater relay out jumper the starter and turns over but no fuel pump running. so something is telling not to crank any steps that i check for… read more
zzdaryl
zzdaryl
Lead Auto Tech
Some college and advanced training
4 satisfied customers
2004 chevy Impala: stall..it kind of sputters and jerks at any rate
we have a 2004 chevy Impala. It has started to stall out at lights and it kind of sputters and jerks at any rate of speed.… read more
Dan
Dan
High School or GED
1,401 satisfied customers
99 Tahoe: cranks..wont start..good fuel pressure..#1 cylinder
99 Tahoe cranks over but won't start. good fuel pressure, have spark at #1 cylinder, no codes set. ?… read more
BOBBYSS
BOBBYSS
TECHNICIAN/ADVISOR
Associate Degree
8,343 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x