dbc2065

92 Eldorado touring coupe

19 posts in this topic

Logan

While back you tried explaning export mode within ipc could you tell me how to reset or make sure it's set to north America? I've gone through everything in this car from top to bottom however still getting backfire timing is at base 10 . Tps is 2.1 iSC is at 13.4 .also injectors flow test? Es10 warm cooler should car be running while in test mode? I'm  getting no check conditions at all. Below is all work by me gm parts car runs great however backfire through intake

PLatium plug 

Delco wires &cap

Fuel pump

Waterpump with inner gasket 

O2 sensor both

Mag flow convertor

Fuel filter

Radiator

Brakes and brake lines front and two metal lines from abs unit left side

Egr valve

Manifold air sensor

Temp sensor

Grille with crest

Alternator

All struts

Ball joints with control arm bushing

End links

Left wheel bearing

All new coolant hoses and gm heater hoses

Air conditioning suction line drier and orfic

Ingintion switch

Rebuilt distributor with gm parts completely 

Power steering pump

All in year time  burn or leak no oil starts right up also keeping carbon free from throttle body

 

 

 

 

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Posted (edited)

Poor engine timing is almost always the cause of intake backfires, but can also be responsible for exhaust backfires. Backfire in the exhaust can also be caused by a rich condition but this will usually set a code.

Does it backfire through the exhaust or the intake? When does it backfire, accel no load or accel under load, at idle or on decel? Was the computer in set timing mode when you checked the ignition timing at 10 degrees?

With the engine off, align your timing marks at TDC #1 cylinder ( be sure you're not aligning on #6 ), raise the distributor cap and the rotor should be pointing directly at the #1 cylinder terminal on the dist cap, not just close, but dead on. If it is not, mark the distributor directly under the #1 cylinder so you have a reference point, raise the distributor and move the rotor one tooth in the direction you need until it lines up directly. When the static timing is set, reconnect the dist cap and wires, put the ECM in set timing mode and start the engine. You can NOT put it in set timing mode with the engine running. Set the timing at 10 deg, turn engine off then remove the jumper and restart.

Note: Firing order 1-8-4-3-6-5-7-2

A lot of people think that because the oil pump drive is slotted you can't get the timing to move one tooth. Use a long flat edge screwdriver and dial it either way to align the slot.

Notice: When you are turning the crankshaft to align the timing marks, make sure you are on the drive side of the timing chain. 

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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I know I just used this guess on another post, but backfire through intake is often a fuel pressure regulator symptom


Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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@Bruce Nunnally        Is there two of these post?  I replied on one.......


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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2 minutes ago, OldCadTech said:

@Bruce Nunnally        Is there two of these post?  I replied on one.......

yes; fixed.


Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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Thanks, :hatsoff:


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Posted (edited)

Tech 

I've double check timing along with correct TDC top side and at crankshaft also DIC timing mode 10 degrees base set. Bruce had told me fuel pressure regulator will cause back fire. There's no hesitation smoking or fuel odor back fire only in park when  engine rev  this problem has been since purchase over year ago and yes there is old post with same complaints of back fire hope Bruce delete all old post to avoid confusion. Guess I'm going to pull regulator off and replace heck everything else has already. Remember old post when check pressure and found drop off but logan said common in gm cars so ignored it however there wasn't any fuel dripping from regulator.

Also replace new winsheld seal

Trans filter

Brakes

To add list above have set of new injectors bought last year while doing fuel pressure regulator will change them as well. However car doesn't have a shake or misfire.  All work I've done except cat convertor and metal brake lines mentioned above. Car is dam near rebuilt lol . Staying on track this past winter inner water jacket gasket began to leak so when I had front cover off timing chain look fine found no play.So you see haven't really cut any corners with the car i'm just stump.  Values was off in icp far as North America  set at 0 because disabled ride control message when change my front struts also correct my miles per mile was off by 5 mile per hour.

Edited by dbc2065

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When I was at the dealer ages ago we had a couple of balancers spin on the 4.9 engine. So when you were setting timing for 8 degrees BTDC you were not setting timing accurately at that #. On a warm engine and a clean tbody with the isc fully retracted the tps should read .57 minimum air and extended isc was 1.2? Its been so long since I have set one up. 

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Thank you backfire has been way before tps and isc adjustment thought read online some where in 93 gm revise the adjustment  to cure sail effect 93-44 think it was called? Are you sure about those settings you gave me? Thanks for your help I love this old car I have 98 percent of mechanical restore gone through before I get cosmetic stuff going clear coat is shot but no body rust.

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@barczy01 Yea, I remember the balancer problem now that you say that. I personally only had one in my stall but I pulled it for a front seal R&R or a front cover reseal and noticed it was bad, so it didn't have anything to do with a timing issue.

@dbc2065  I'm still convinced it is timing. I put a 4.1 HT back together and it backfired on accel - no load, the same as yours is. Reset the distributor and timing, worked fine. I don't remember a 92 being timed through the DIC either, not that I would have done it that way anyway. I would highly recommend checking the balancer and see if it has moved. 

First though, for giggles, I would connect a vacuum gauge and set timing for highest vacuum and see what happens.


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Timing through DIC no but DIC tells you in time mode 

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Must be misunderstanding thanks for all in put. I have fsm book .I'm to go with Bruce said fuel pressure regulator with intermittent back fire. Caddy I've check all timing you mention long ago following fsm with jumper and TDC checking right on mark. Grateful for your knowledge just trying to solverify this problem for a year about the time became a member and purchase my car.

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Yes, I did misunderstand your statement about the DIC showing the 10 degrees. 

BUT, a backfire is fuel being ignited at the wrong TIME. The 4.9 is a port fuel injected engine so fuel is not pooling in the intake. 

22 hours ago, dbc2065 said:

There's no hesitation smoking or fuel odor back fire only in park when  engine rev

If you're talking about a lean miss and not an actual backfire, fuel pressure would be more of an issue. If you increase rpm past around 4500 in park or neutral it will hit the rev limiter which may sound like a backfire, especially with the intake assembly off the engine.

On 8/18/2017 at 9:34 PM, dbc2065 said:

Below is all work by me gm parts car runs great however backfire through intake

2 hours ago, dbc2065 said:

I'm to go with Bruce said fuel pressure regulator with intermittent back fire.

Is it intermittent or can you make it happen if you want?

 

 


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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First my email Grammer isn't the best sorry back fire happens only at idle when rev up engine below 4,500 rev limited you mention.this problem has always  been since purchase car. I've even check my settings both on timing  and thottlebody. 10 degrees on timing. Air mixture screw isn't touching throttle. ISC 13.0 tps is +1.1  all new vacuum lines throttle body and egr port are clean spotless.  Would leaky injector cause backfire I think you told yes a while back about a year ago.

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2 things. 

There is a 'set timing mode' the car has to be in to properly set the ignition timing. 

 

What it sounds like is really happening.....

When the car is in park....you can only rev it so far before the computer will start turning it off.....a rev limiter. It sounds like it is getting into the rev limiter. That would be a normal vehicle operating condition. 

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Posted (edited)

Logan

Thank's well aware of set timing steps also checking for correct TDC as discussed in prior thread above. Also my car only backfire in park only  not necessarily at rev limited as your saying it's intermittent  I've  triple check timing TDC  on top also at crankshaft and firing order at wires all new parts  disburtor is rebuilt also  which is why listed parts or work I've done in past year.  While driving there's no back fire car respond well no smoke from exhaust no check lights  no oil burn or leaks. I'm  to look in direction Bruce has mentioned to me fuel pressure regulator  which hasn't been changed  however fuel pump has been replaced .

 

Grateful for your help though

Edited by dbc2065

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Posted (edited)

14 hours ago, OldCadTech said:

If you increase rpm past around 4500 in park or neutral it will hit the rev limiter which may sound like a backfire, especially with the intake assembly off the engine.

 

11 hours ago, Logan said:

When the car is in park....you can only rev it so far before the computer will start turning it off.....a rev limiter.

As Logan and I both stated, you seem to be trying to correct a normal condition. If you can capture a cell phone video and audio post it here. I'm more convinced than ever, you're hitting the rev limiter. 

Save your money, the fuel pressure regulator does NOT need to be changed. If the  FPR was defective it would happen in gear under load, or most likely at cruise speeds.

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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With respect i'm hitting rev limited to get back fire within intake about 3,000 or less intermittently.  Like said this problem been trying to solve for over a year even completely tune car via work I've listened above with parts list or work except for fuel regulator and injectors with I have new in parts box even then it might be a waste of labor because this car really drives well with exception back fire within intake . Tech if you have a minute won't be a bother quick phone call it might clear up confusion 701 850 6451

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