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After replacing head gasket 350 Vortec is a pig to start and…

Hi...after replacing head gasket...

Hi...after replacing head gasket 350 Vortec is a pig to start and delays acceleration

Mechanic's Assistant: Is this your first time dealing with this issue? What size is your engine?

Small block 5.7 thanks. Yes started fine before just damaged head gasket on one cylinder

Mechanic's Assistant: What is the model/year of your Chevy?

1998 CK

Mechanic's Assistant: What can I say?

Fault code says crank/cam or Maf sensor

Mechanic's Assistant: What can I say?

Thinking perhaps advance the timing a little..what do you think?

Mechanic's Assistant: What year is your Chevy?

1998

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

Timing is correct..cleaned the MAF and the CPS

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

Engine low miles ..

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Answered in 7 minutes by:
8/21/2017
david craig
david craig, Auto Mechanic
Category: Chevy
Satisfied Customers: 5,767
Experience: owner/mechanic at 3D Automotive
Verified

Hi Im David, thanks for visiting the site. What are the fault codes?

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Customer reply replied 10 months ago
Hi David sorry for the delay in answeringP1345
Customer reply replied 10 months ago
We have cleaned the MAF and crank sensor

no problem, thanks

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Customer reply replied 10 months ago
Are you still there?

yes im here, please have a little patience

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Customer reply replied 10 months ago
sure..sorry

thanks

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try adjusting the distributor. I have attached the complete diagnostic for the code, but adjusting the dizzy would be the first thing I would try.

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Customer reply replied 10 months ago
Thanks david..shall i advance it a little

try advancing yes

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Customer reply replied 10 months ago
Ok thanks..i will get back to you shortly DavidCarl

Ill be here

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Customer reply replied 10 months ago
Hi david...tried advancing and retarding the distributor..still just about impossible to start.
revs to the high range ok but chokes on accelerating

ok, standby

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this is a failure of the cam and crank sensor working together. a scan tool is going to need to be used to troubleshoot this to see what sensor is reading offset from the other.

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Customer reply replied 10 months ago
Thanks...maybe i will buy both sensors ..good idea you think..as a short cut?

I never like to replace anything until I know its bad.

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Customer reply replied 10 months ago
Understood but we used a different diagnostic tool and it came up with the same code P1345.
Does that fault code not include the MAF sensorWe are also unable to clear the engine warning light.

its definitely a hard fault for sure. maf sensor has no input to the code whatsoever

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it doesnt matter what scan tool you use, the code is the code. it needs to be diagnosed accordingly.

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if you want to take your chances by replacing both sensors, have at it. but I would check the power, ground and signal at the sensors.

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Customer reply replied 10 months ago
Ok..the crank sensor has 3 pins..what should i read from them?
Similarly how do i test the cam sensor and MAF
Thanks

ok, please give me a while to get those tests together for you. thanks.

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crank sensor test

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more info for you.

http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/how-to-test-the-cam-sensor-1

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Customer reply replied 10 months ago
Good stuff David..i will leave in [peace for a whileRegards
Carl

ok, if you follow that information, you will determine if its a wiring issue or a component issue for sure.

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please accept the answer and leave a 5 star rating for me if you are satisfied with my assistance. just remember, by accepting the answer and leaving a rating doesnt mean we are done. im here to help you until the vehicle is fixed.

david craig
david craig, Auto Mechanic
Category: Chevy
Satisfied Customers: 5,767
Experience: owner/mechanic at 3D Automotive
Verified
david craig and 87 other Chevy Specialists are ready to help you
Ask your own question now

thank you much and let me know if theres any more information or assistance that you need.

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Customer reply replied 10 months ago
hi David..replaced cam and crank sensors.
The difference now is that we can clear the engine warning light and no other codes.
Still a pig to start and excessive cranking brings up the engine light again.
My mechanic thinks its an air leak symptom?
The only gasket we did not fit new when doing the head gasket was the inlet manifold one.
What do you think?

the lower intake manifold gasket wasnt replaced?

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Customer reply replied 10 months ago
No..just cleaned and reused the old one with some silicon.
When you say lower gasket..is there not just one?
Customer reply replied 10 months ago
My apologies the lower ones were replaced new..but the upper one between aluminium and plastic was not replaced

spray around the intake manifold and plenum, all vacuum hoses and connections and the brake booster with carb cleaner and check for an rpm change

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Customer reply replied 10 months ago
Fire risk?

not with carb cleaner

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Customer reply replied 10 months ago
no surge with applying carb cleaner.
Car starts fine first thing and engine warning light stays off.
Restart after 5 mins max and reluctant to start . The engine warning light comes on.
We have checked the timing ..perfect.
Replaced the crank and cam sensors.
No fault codes...does this leave the MAF at fault> ?

if the maf was faulty it would code. but you can test it.

http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/how-to-test-the-maf-sensor-2

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hows it going?

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Customer reply replied 10 months ago
Hi David..i dont have a digital meter with Hertz

are you talking about checking the signal from the maf?

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Customer reply replied 10 months ago
thats right

just use the voltage to check the signal by back probing the connector while cranking the engine

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Customer reply replied 10 months ago
to be clear..cable A should pulse some sort of voltage?

yes you should get a dc voltage reading

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Customer reply replied 10 months ago
Cheers..will try it

ok

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Customer reply replied 10 months ago
David..we tested the MAF sensorBlack wire has a good earth
Red wire is grounded with ign off...12.7 volts with ign onYellow wire (with engine running) fluctuates between 0-4.2 volts about every second
Yellow wire ..when unplugged from MAF fluctuates between 0-5.0 volts about every second

well that tests good.

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is it still taking a long time to start?

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Customer reply replied 10 months ago
first start is fine.
second start even after 3 mins is hard

how about doing a fuel pressure leak down test

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Customer reply replied 10 months ago
How do i do that please

standby

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fuel pressure test and leak down test,

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david craig
david craig
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