Loss of Power and Jerking!

[GregBPAU]

Car is a 1995 Buick park avenue Ultra
Series I L67 Supercharged and 4T60E transmission.

The issue is jerking, back and forward like you are being shaken, and not being able to go past 3500 rpm.

Car drives fine if you don't step on the gas and if you disconnect the battery and re- connect it, The car can drive as fast as an arrow. but after restart if the car gets warm its game over

This issue originates when the engine gets unusually hot.

When in neutral, the engine happily revs to 4k and the injectors limit the revs like designed.

The old ECU threw codes regarding both the cam an crank sensor but i changed both

the only thing that really made a difference was changing the Ignition module but after changing the ECU the check engine light finally turned off, but the problem is back.

Something somewhere is triggering something that causes stumbling, jerks and loss of power when the car gets hot.

The only thing I haven't really replaced is the MAF sensor. Or anything Fuel related. Maybe a degraded Fuel pressure regulator will deliver insufficient fuel when hot?

I'm on my second ECU. Second set of coils, Changed all sensors except of the maf and EGR...

 

[02LTD2.0]

Have you tried cleaning the MAF and EGR?

 

[GregBPAU]

Have you tried cleaning the MAF and EGR?

Hi! Thanks for commenting!

So far I have only cleaned the MAF and visually inspected the EGR, it's unusually clean.

I am unsure as to addressing this issue first or going straight for the water pump and avoiding engine overheating in the first place. (If left in idle the temp reaches 110C.) sometimes the fans won't kick in. And the displayed temp in the gauge doesn't correspond to the temp I get with the diagnostics tools.

I will re-check the EGR valve and clean it thoroughly, and I will to the same with MAF just for good measure.

Regards from Spain

 

[BuickGirlFromMars]

Car is a 1995 Buick park avenue Ultra
Series I L67 Supercharged and 4T60E transmission.

The issue is jerking, back and forward like you are being shaken, and not being able to go past 3500 rpm.

Car drives fine if you don't step on the gas and if you disconnect the battery and re- connect it, The car can drive as fast as an arrow. but after restart if the car gets warm its game over

This issue originates when the engine gets unusually hot.

When in neutral, the engine happily revs to 4k and the injectors limit the revs like designed.

The old ECU threw codes regarding both the cam an crank sensor but i changed both

the only thing that really made a difference was changing the Ignition module but after changing the ECU the check engine light finally turned off, but the problem is back.

Something somewhere is triggering something that causes stumbling, jerks and loss of power when the car gets hot.

The only thing I haven't really replaced is the MAF sensor. Or anything Fuel related. Maybe a degraded Fuel pressure regulator will deliver insufficient fuel when hot?

I'm on my second ECU. Second set of coils, Changed all sensors except of the maf and EGR...

issue sounds like spark plug wires or plugs. Send pictures of your wires to the plugs and your ignition control module and the wiring to it

 

[GregBPAU]

Hi! Thanks for commenting

The wires are prestolite and the plugs are A Delco . All done last summer.

One wire leading to the ICM has had some insulator stripped, probably to attach a Crocodile clip.

I hope to hear more from you.

Best regards from Spain!

 

[BuickGirlFromMars]

Remove that tape and inspect the wire condition, thats not a proper repair
with the engine idling, spray water with a bottle of water that has a mist section near the wires along the length, and watch for sparking

The pcv should be removed and inspected and cleaned, there is also a baffle under it that is hard to remove that should be cleaned out

 

[GregBPAU]

Remove that tape and inspect the wire condition, thats not a proper repair
with the engine idling, spray water with a bottle of water that has a mist section near the wires along the length, and watch for sparking

The pcv should be removed and inspected and cleaned, there is also a baffle under it that is hard to remove that should be cleaned out

Hi! Thanks again for reaching out.

Now that you mention it. The engine runs differently when I open the oil filler cap.

I have replaced the pcv but wasn't aware there was a removable baffle right below it. Will definitely check these things you mention and post the results.

Regards

 

[GregBPAU]

Remove that tape and inspect the wire condition, thats not a proper repair
with the engine idling, spray water with a bottle of water that has a mist section near the wires along the length, and watch for sparking

The pcv should be removed and inspected and cleaned, there is also a baffle under it that is hard to remove that should be cleaned out

Hi. I have just Recorded a 30 minute test drive with tuner pro. Also discovered a new unexpected code: 171 fuel trim lean. I am going to upload the recording and the xdf and adx files so anyone can visualize the behavior of the sensors, dash and error codes.

Edit: I have replaced the MAF with a Remanufactured unit from Ac Delco.

 

[GregBPAU]

To anyone who can lend me a hand with this and figure out what is wrong with my car I am willing to send Payment if necessary. I have no experience with American cars and nobody here in Spain is specialized in early electronics in US cars.

I will have to send the .xdf .adx files per e-mail as this forum doesn't allow these files on the page.

 

[02LTD2.0]

You need to check for vacuum leaks.

 

[GregBPAU]

You need to check for vacuum leaks.

hi! Thanks for steering me into the right direction...

Visually all lines seem to be in ok shape. Will disassemble the vacuum distributors and look for blockages. Last thing to check are the lower and upper intake manifold gaskets. IF the rpms rise when spraying starting fluid I have bad gaskets.

There is also a strange line with a piece of foam glued to it coming from the Supercharger bypass valve. It probably opens the opposite side of the membrane to atmospheric pressure so that the valve can operate. If it's blocked maybe the bypass valve opens and closes violently causing the jerks.

A lean fuel trim can also explain why my car heats up so fast. If it ran richer the temperature would drop. Or at the very least not rise uncontrollably. I have changed the water pump thinking Dex cool had eaten away the fins in the water pump. But no, it was in perfect shape. Car has Only 99.000 km but I suspect the engine isn't the original one. There are bad welding spots in the underside of the carriage

I really do suspect now there is something very wrong with the gaskets because the engine always sweats oil. There is no continuous leaks. But the oil pan is always covered with a thin film of oil. (Color and consistency of oil is ok but smells a little bit like gas)

Also, looking inside the coolant reservoir tank there are specs of iron or other fine debris inside. I flushed the coolant system with distilled water 4 times and let evapo-rust sit inside and do it's work for 3 full days.

Then flushed again with distilled water and filled with Motul Auto cool .

 

[GregBPAU]

Remove that tape and inspect the wire condition, thats not a proper repair
with the engine idling, spray water with a bottle of water that has a mist section near the wires along the length, and watch for sparking

The pcv should be removed and inspected and cleaned, there is also a baffle under it that is hard to remove that should be cleaned out

Hi! The wire going into the ICM was in ok shape, it was missing the insulator. So I decided to splice it and put two layers of heat shrink on it so I can protect it from the elements.

 

[HotZ28]

hi! Thanks for steering me into the right direction...

Visually all lines seem to be in ok shape. Will disassemble the vacuum distributors and look for blockages. Last thing to check are the lower and upper intake manifold gaskets. IF the rpms rise when spraying starting fluid I have bad gaskets.

You might be right!

There is also a strange line with a piece of foam glued to it coming from the Supercharger bypass valve. It probably opens the opposite side of the membrane to atmospheric pressure so that the valve can operate. If it's blocked maybe the bypass valve opens and closes violently causing the jerks.

Has the engine lost power/bosst pressure?

I really do suspect now there is something very wrong with the gaskets because the engine always sweats oil. There is no continuous leaks. But the oil pan is always covered with a thin film of oil. (Color and consistency of oil is ok but smells a little bit like gas)

You may have a leaking fuel pressure regulator if you smell gas in the oil! .

Then flushed again with distilled water and filled with Motul Auto cool .

Have you ever changed, or replaced the thermostat?

 

[GregBPAU]

You might be right!

You may have a leaking fuel pressure regulator if you smell gas in the oil! .

Have you ever changed, or replaced the thermostat?

Hi!

I replaced the FPR and now no more Fuel trim Lean

I have changed the Thermostat and water pump with Gates 180F. Looking at the insides of the radiator it might need replacing soon.

Trouble I have now is an intermittent current drop. It like the ignition turned off and on in a milisecond,and all dash light are red. Only trouble code it displays is Change oil soon.

I suspect a bad alternator or faulty ECU/PCM .

New ECU is on it's way, and I will look for the correct alternator. Turns out I was running the 105 Amp alternator with sheet metal fin ventilator blades when the correct alternator is the one with the cast iron fins and 140Amp Output.

Maybe that's why the generator was getting so hot and the voltage indicator in the dash flickers when I put the turn signal.

 

[HotZ28]

How old is the battery & has it been load tested? Are the battery connections clean & tight? What makes you think the original alternator was 140 amp? does the SPID code on the spare tire cover show

"KG9	"GENERATOR,140 AMPERE 140 AMP(KG9)?

 

[GregBPAU]

How old is the battery & has it been load tested? Are the battery connections clean & tight? What makes you think the original alternator was 140 amp? does the SPID code on the spare tire cover show

​

"KG9	"GENERATOR,140 AMPERE 140 AMP(KG9)?

Hi!

I had my Vin decoded and it says exactly KG9 140 amp Generator!

Turns out the previous owner had burned the previous alternator and was running on a old battery.

The first thing I did was put a new battery,date is 0724 and the first replaced part was the alternator. Maybe all my troubles are lack of current related?

Will keep you posted

 

[HotZ28]

The 105 amp alternator should be sufficient to keep the battery charged, unless you have a 2000K amp system with 4-12" speakers! Has the voltage of the battery been checked & battery load tested? What is the battery voltage with the engine OFF & with engine running?

 

[GregBPAU]

The 105 amp alternator should be sufficient to keep the battery charged, unless you have a 2000K amp system with 4-12" speakers! Has the voltage of the battery been checked & battery load tested? What is the battery voltage with the engine OFF & with engine running?

The battery is probably ok it's barely a year old. I'll go check the voltages out anyways, will put the stereo on and, turn on the lights and turn the climate on full to create some draw.

The battery may not be as heavy duty or has the cranking power of the original one but it is probably sufficient and doesn't bulge or get warm.

I also ordered some battery terminal adapter connectors. From universal terminals to 3/8 threads. No one carries American style screw on type batteries here. So had to do a questionable and homemade remedy to connect the battery.

Weird thing I noticed is, the alternator conector has 4 pins but the cable connector has only one red cable going into the harness.

I hope that the new alternator, and battery adapters help get the car back on it's feet. If not, in goes a new ECU. And if it still starts to fail I will have to look for professional help, and translate the whole Electric systems manual for them into Spanish...

Please Pray for me

 

[HotZ28]

I will be praying for you, but you need to check the battery connections to be sure the "No one carries American style screw on type batteries here. So had to do a questionable and homemade remedy to connect the battery." That could be the problem if the bolts are to long! Answer my questions about battery voltages with the engine running & not! In addition, test both again while trying to move them around the battery connections.

 

[GregBPAU]

Hi! I just made sure to do the voltage tests you mentioned.
Engine off reading: 12.95V
Engine ON no load: 14.1V
Engine ON wih Load 13.90V

I just decided to install the old ECU again, the ecu that came with the car. to test if it runs better.The unit itself is allready a DELPHI reman unit. and it does work well, it shifts nice, sounds better. but the Check engine light is back on
On the first Run , the traction off light was on
On the second Run, The traction off light was no longer on but the check engine light indicated P0321 18x interrupt.
On the third Run Check engine was stil on, Codes: P0321 and P0361 EST Line not Toggling.
On the 4th run the check engine was on and the traction controll light was also on. Error codes same as before

The Memcal on my ECU says Delco BKKF 1386 ... Strange the GM BCC lookup says manual transmission.

At this point I can only assume that the ECU is bad because the other ECU I had installed didn't have any check engine light but the ignition would cut off intermittently, followed by a Change oil soon light. Faulty unit.

I am completely lost.

I will perform the Crank and Cam sensor tests from the 94 Manual and see if voltages are ok.

I am going to Throw more money into it, Put the correct alternator in, Get actual adapters for the battery terminals and two more ECUs,

IF that fails i will just cover the check engine light with a piece of tape.