Sluggish power after changing brake rotors (Page 3/4)
Jason88Notchie MAY 26, 12:41 PM
Ok. If there is a suspicion of clogged exhaust this is an easy way to test for it. This kit is from Amazon.




On the initial diagnosis. See contaminated fuel and fuel pressure from above FSM post. If symptoms start to worsen change fuel filter ASAP.

Keep in mind it's possible to be fighting both conditions at same time.

danahart JUN 01, 01:06 PM
New information: I also added this to the bottom of the top post.

Tested the fuel pressure. Primed it reads 40psi. When running it started at 35psi but went to 40 when driving. When stopped and turned off, pressure still read 36psi a half hour later. 12 hrs later it read 23psi. That all seems normal based on my internet reading so I assume I can rule out the fuel pump? I also changed the fuel filter. Changed pretty easily so I doubt it was the original one or super-old. Test drove and no change although the warning code 44 is no longer displaying...but I also didn't drive for more than 15min or so.

Not sure what to check next...



quote
Originally posted by danahart:

Hi all. Pretty new poster but have read a bunch on this forum. I just got a 1988 Formula a few weeks ago so am new to the Fiero world. Also pretty inexperienced mechanic skills but hoping to improve that now that I have a 30yr old car. Looking for advise on an issue I'm having.

Anyway, the car is a v6 manual and worked perfectly at time of purchase. I didn't drive it too much due to the very bad tires but enough to get an idea of how it felt. I finally got new wheels on it and went ahead and put new rotors on as well since the old ones were pretty rusty and the car came with a brand new extra set. I didn't change the brake pads as they looked fine. All good and I started driving it fairly regularly on short trips.

A few days later I noticed the car doesn't have as much power as I remembered. I don't think this happened at the same time as the brake/wheel work...I'm fairly sure it ran as normal for a few days before I noticed the lack of power. But it is somewhat subtle and if I'm not trying to quickly accelerate it can be easy to miss. I only mention the wheel/brake work as it is the only thing I've done to the car. Just to test to make sure there wasn't rubbing or locked up, while off I disengaged the ebrake and pushed the car back and forth on a flat driveway...it pushed very easily. I figured that if anything was rubbing I'd have heard or felt the resistance. Educate me if that is not a valid assumption.

Anyway, the car can get up to speed but it doesn't have the acceleration it used to. I almost have the accelerator touching the floor in first gear before I get moving enough to go to 2nd. Once moving it can maintain speed but again, just lacks power. I'll be in 4th on a slight hill going around 50 and have to have the pedal to the floor to maintain that speed in that gear. It is also struggling to get up my steep driveway in 1st a bit.

I haven't had a lot of time to investigate, the only thing I've done so far is to check the air filter to make sure there wasn't a blockage keeping air from getting in. All seemed ok there. I plan to pull the wheels and doublecheck the brakes again just to make sure I didn't mess something up...but again I figure that if I can freely spin the wheel then that should eliminate that possibility, right?

Any ideas on what the likely culprit is or the easiest things I could start to check first?

EDIT: No cat on the car.

UPDATE:
- 5/24: added the LinquiMolly fuel additive with a new tank of gas. Today I ran out for a short errand and the Service Engine Soon light came on. I checked and it is throwing code 44: Lean exhaust indicated (Left side on dual oxygen modules). I looked through the forum and it seemed there were a bunch of possible causes for this but maybe someone has a suggestion on this code combined with my loss of pep.

-Changed the air filter at some point I forget when.

- 6/1: Tested the fuel pressure. Primed it reads 40psi. When running it started at 35psi but went to 40 when driving. When stopped and turned off, pressure still read 36psi a half hour later. 12 hrs later it read 23psi. That all seems normal based on my internet reading so I assume I can rule out the fuel pump? I also changed the fuel filter. Changed pretty easily so I doubt it was the original one or super-old. Test drove and no change although the warning code 44 is no longer displaying...but I also didn't drive for more than 15min or so.

Not sure what to check next...
Jason88Notchie JUN 02, 10:27 AM
Reread the thread. There are other items to check off the list. I would check your exhaust back pressure first. You'll need the backpressure gauge and a timing light to check your ignition timing. Did the previous owner give you a list of things done recently before you purchased the car? That is especially good info to know.
danahart JUN 02, 10:45 AM
I've ordered the OBDC reader which should come here soon. I'll also do the exhaust test and see


quote
Originally posted by Jason88Notchie:

Reread the thread. There are other items to check off the list. I would check your exhaust back pressure first. You'll need the backpressure gauge and a timing light to check your ignition timing. Did the previous owner give you a list of things done recently before you purchased the car? That is especially good info to know.
Jason88Notchie JUN 02, 10:57 AM

quote
Originally posted by danahart:

I've ordered the OBDC reader which should come here soon. I'll also do the exhaust test and see




Remember. If it's a "newer scanner" make sure it will read OBD 1.
Jason88Notchie JUN 02, 11:11 AM
Oh, quick thought. Where did you fill up the last two times? What are the options stations you have near you?
danahart JUN 02, 11:34 AM
I've only filled up twice. The first I don't recall but just used regular 87. The most recent time I filled up, I used premium. I'm sure I have access to about everything in my area if there is something you think would make a difference.


quote
Originally posted by Jason88Notchie:

Oh, quick thought. Where did you fill up the last two times? What are the options stations you have near you?
Jason88Notchie JUN 02, 12:29 PM
I use 2 different fuels. Shell and Speedway (Speedway owned by Marathon, very large in my region). Theogre likes Chevron which is a good choice. I don't have very many of those locally.

I'm pickier with fuel in the Fiero. My 2007 Buick not so much. Just try to be consistent when you can. I have gotten a bad batch of gas one time from Speedway. I was not happy. It can happen.
danahart JUN 06, 08:43 PM
Problem identified. I found out today that 3 cylinders were not firing, all on the rear side. Some online search led me to the fact that the fuel injectors have 2 fuses that can get blown. Sure enough I had a blown fuse. Replaced it and everything was perfect and back to normal. Thought I was good but the fuse blew again when I started the car up later. Old forum posts tell me that I likely have a short in the ignition harness someplace. I'm going to start a few forum topic about this if I can't find that short tomorrow and need more help. Thank you all for your willingness to try to help me.


quote
Originally posted by danahart:

Hi all. Pretty new poster but have read a bunch on this forum. I just got a 1988 Formula a few weeks ago so am new to the Fiero world. Also pretty inexperienced mechanic skills but hoping to improve that now that I have a 30yr old car. Looking for advise on an issue I'm having.

Anyway, the car is a v6 manual and worked perfectly at time of purchase. I didn't drive it too much due to the very bad tires but enough to get an idea of how it felt. I finally got new wheels on it and went ahead and put new rotors on as well since the old ones were pretty rusty and the car came with a brand new extra set. I didn't change the brake pads as they looked fine. All good and I started driving it fairly regularly on short trips.

A few days later I noticed the car doesn't have as much power as I remembered. I don't think this happened at the same time as the brake/wheel work...I'm fairly sure it ran as normal for a few days before I noticed the lack of power. But it is somewhat subtle and if I'm not trying to quickly accelerate it can be easy to miss. I only mention the wheel/brake work as it is the only thing I've done to the car. Just to test to make sure there wasn't rubbing or locked up, while off I disengaged the ebrake and pushed the car back and forth on a flat driveway...it pushed very easily. I figured that if anything was rubbing I'd have heard or felt the resistance. Educate me if that is not a valid assumption.

Anyway, the car can get up to speed but it doesn't have the acceleration it used to. I almost have the accelerator touching the floor in first gear before I get moving enough to go to 2nd. Once moving it can maintain speed but again, just lacks power. I'll be in 4th on a slight hill going around 50 and have to have the pedal to the floor to maintain that speed in that gear. It is also struggling to get up my steep driveway in 1st a bit.

I haven't had a lot of time to investigate, the only thing I've done so far is to check the air filter to make sure there wasn't a blockage keeping air from getting in. All seemed ok there. I plan to pull the wheels and doublecheck the brakes again just to make sure I didn't mess something up...but again I figure that if I can freely spin the wheel then that should eliminate that possibility, right?

Any ideas on what the likely culprit is or the easiest things I could start to check first?

EDIT: No cat on the car.

UPDATE:
- 5/24: added the LinquiMolly fuel additive with a new tank of gas. Today I ran out for a short errand and the Service Engine Soon light came on. I checked and it is throwing code 44: Lean exhaust indicated (Left side on dual oxygen modules). I looked through the forum and it seemed there were a bunch of possible causes for this but maybe someone has a suggestion on this code combined with my loss of pep.

-Changed the air filter at some point I forget when.

- 6/1: Tested the fuel pressure. Primed it reads 40psi. When running it started at 35psi but went to 40 when driving. When stopped and turned off, pressure still read 36psi a half hour later. 12 hrs later it read 23psi. That all seems normal based on my internet reading so I assume I can rule out the fuel pump? I also changed the fuel filter. Changed pretty easily so I doubt it was the original one or super-old. Test drove and no change although the warning code 44 is no longer displaying...but I also didn't drive for more than 15min or so.

Not sure what to check next...
Patrick JUN 06, 08:49 PM

quote
Originally posted by danahart:

Old forum posts tell me that I likely have a short in the ignition harness someplace.



One of the INJ fuses is on the same circuit as the EGR solenoid.


quote
Originally posted by danahart:

Today I ran out for a short errand and the Service Engine Soon light came on. I checked and it is throwing code 44: Lean exhaust indicated (Left side on dual oxygen modules). I looked through the forum and it seemed there were a bunch of possible causes for this but maybe someone has a suggestion on this code combined with my loss of pep.




quote

Code 44

Oxygen Sensor - Lean Exhaust
The ECM will set code 44 when the ECM detects a low voltage from the oxygen sensor and the system is operating in Closed Loop (conditions must exist for longer than 20 seconds).

Check the wires of the oxygen sensor, making sure they are not in contact with the exhaust manifold.

Check the oxygen sensor and replace if necessary.

Check the MAP sensor. If the ECM detects a higher than normal vacuum then this will cause the system to go lean. Disconnect the MAP sensor. If the lean condition goes away, then a problem exists with the MAP sensor.

Check for lean injectors.

Check for fuel contamination (specifically for contamination with water).

Check fuel pressure. If pressure is too low, the system will be lean.

Check for exhaust leaks. An exhaust leak can cause air to be pulled into the exhaust and past the sensor.

If you have spark knock, check the EGR system.



I suspect your EGR solenoid possibly isn't functioning (maybe shorted internally or otherwise).

[This message has been edited by Patrick (edited 06-06-2024).]