When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello, new to the forum , I’ve used a lot of help from all the generous people on here however I’m having issues with 94 lt1 pass smog , the car is BONE STOCK and the only thing done to it is the exhaust and new carb comp catalytic converter , so upon first fixing the egr issue which was causing ses light. I took it over to a smog station and had it smogged , here are the results:
The car didn’t pass , so I brought it home switched out the egr solenoid only cleaned valve since the actual valve was functioning properly. I also did an oil change , new coolant , and new air filter and took it back. The results were
again , I brought the car home and started looking for the next issue. That’s when I realized I had a misfire and one of wires was completely loose , I also noticed half of the spark plugs were loose and while I was already all that I switched out the opti , the car starts up fine and has no isssues up until it gets warm it starts making a popping noise of the exhaust as well as when you floor it the car cuts out for a second and then pulls hard again , but immediately after flooring it the ses lights comes back on. I’m pretty sure the popping has something to do with the ses light and the high nox since I’m thinking the car is running lean , does anyone have any idea what the issue could be or any suggestions to lead me in the right direction , I’m thinking it could be the o2 sensors but I do not have the tools to do any testing.
Running hot also increases NOx emissions. What does your coolant temp look like when smog test is being run? EGR passages in manifold may be plugged up.
Based on your description, car seems to be suffering from poor maintenance - bad plug wire, loose spark plugs.
What changes have been made to the exhaust ("car is BONE STOCK and the only thing done to it is the exhaust ")?
You indicate "I do not have the tools to do any testing." How did you determine in the initial test that the SES light was on because of the EGR valve? Do you have a code scanner? If so, what it the new code for "the ses lights comes back on"?
When you swapped the Opti are you sure you indexed the splined shaft correctly to the cam sprocket? What brand new Opti?
In spite of the shaft being "keyed" seems like about 5 to 10% of the installs manage to somehow assemble the splines incorrectly.
Given the number of issues, best thing to do is run a PCM data log using Scan9495. I've stopped reviewing these for people, but in this case I don't know how else to sort this out.
If you decide to use Scan9495, please be sure to read the guidelines for running the data log (post #2 in link below). Amazing how many people don't read, or don't follow the guidelines.
Running hot also increases NOx emissions. What does your coolant temp look like when smog test is being run? EGR passages in manifold may be plugged up.
Based on your description, car seems to be suffering from poor maintenance - bad plug wire, loose spark plugs.
What changes have been made to the exhaust ("car is BONE STOCK and the only thing done to it is the exhaust ")?
You indicate "I do not have the tools to do any testing." How did you determine in the initial test that the SES light was on because of the EGR valve? Do you have a code scanner? If so, what it the new code for "the ses lights comes back on"?
When you swapped the Opti are you sure you indexed the splined shaft correctly to the cam sprocket? What brand new Opti?
In spite of the shaft being "keyed" seems like about 5 to 10% of the installs manage to somehow assemble the splines incorrectly.
Given the number of issues, best thing to do is run a PCM data log using Scan9495. I've stopped reviewing these for people, but in this case I don't know how else to sort this out.
If you decide to use Scan9495, please be sure to read the guidelines for running the data log (post #2 in link below). Amazing how many people don't read, or don't follow the guidelines.
The coolant temp is at a centimeter over the middle mark . When I bought the car it wasn’t even running due to the mechanic doing a hack job. They didn’t route the wires correctly to the opti and the valves were completely out of wack. It was poorly maintained but I’ve so far changed plugs , wires and opti already as for the exhaust it’s just a muffler delete and tips . No exhaust leaks. Now the ses was caused by the egr solenoid just being unplugged, when I plugged it back in the the light won’t come on . The opti I did make sure the spline was put in correctly and the reason for me changing this one again was because I had seen the main seal was leaking a lot of oil all over it as well so I switched out a second time. (First time being when I got the car).
Here’s an example of the popping noise I’m hearing out of the exhaust when it warms up . I don’t know if you’ll be able to hear it but the best way I can describe it is like a random popping noise you’d make with your mouth .
Those are the codes it threw , about 6 of em .-. Idk where I should start. I suspected the o2 sensors which I was right about as well as the maf any suggestions ?
What brand scanner are you using? There are Equus and Innova scanners that give numerous false codes because they have a corrupt database for the LT1 engine.
1. Are those codes indicated as "stored" or "active"?
2. Does the SES light comes on ONLY when you put the accel pedal on the floor?
3. Does the SES light go off when you back off on the pedal?
There are contradictions in these codes setting all at once, like when you floor the accel pedal. Best thing to do would be clear the codes (pull "PCM BAT" fuse for 30 seconds) and drive the car again. Go full throttle, and if the SES light comes on, immediately check for codes. If you were running a Scan9495 data log while doing this, it would be a lot easier to decipher what is causing the problems.
DTC 26 EVAP Canister purge Solenoid Valve Circuit - Sets when the power supply to the EVAP purge solenoid is open or shorted.
DTC 34 MAP Sensor Circuit - Sets when MAP reading is irrationally low (<16 kPa). Sets when MAP = less than 16 kPA and RPM lower than 700, or when MAP = less than 16 kPa and RPM over 700, throttle angle greater than 26%.
DTC 36 Distributor (Opti) Ignition System - Sets when faulty high resolution pulse or extra low resolution pulse detected. The effect of this code is very minor, causing a slight loss of accuracy in spark timing.
DTC 41 Ignition Control Circuit (Open Circuit) - Sets when the ICM does not receive the pulses from the PCM that tell the ICM to fire the coil. Engine would not run with this code active.
DTC 44 Bank 1 O2 Sensor Circuit (Lean exhaust indicated) - This code cannot set in "Power Enrichment" mode, which is typically where the engine is operating at WOT or close to WOT (depending on RPM). Sets when the O2 sensor indicates less than 200mVolts for 50 seconds.
DTC 48 MAF Sensor Circuit - Sets when the engine is running (PCM detects reference pulses from Opti) but there is no frequency signal from the MAF sensor. Likely an open circuit.
What brand scanner are you using? There are Equus and Innova scanners that give numerous false codes because they have a corrupt database for the LT1 engine.
I have no clue , I ran these at smog place before arriving I floored it so the ses light would come on , it’s very consistent turns on every time after flooring it.
1. Are those codes indicated as "stored" or "active"?
2. Does the SES light comes on ONLY when you put the accel pedal on the floor?
3. Does the SES light go off when you back off on the pedal?
There are contradictions in these codes setting all at once, like when you floor the accel pedal. Best thing to do would be clear the codes (pull "PCM BAT" fuse for 30 seconds) and drive the car again. Go full throttle, and if the SES light comes on, immediately check for codes. If you were running a Scan9495 data log while doing this, it would be a lot easier to decipher what is causing the problems.
DTC 26 EVAP Canister purge Solenoid Valve Circuit - Sets when the power supply to the EVAP purge solenoid is open or shorted.
DTC 34 MAP Sensor Circuit - Sets when MAP reading is irrationally low (<16 kPa). Sets when MAP = less than 16 kPA and RPM lower than 700, or when MAP = less than 16 kPa and RPM over 700, throttle angle greater than 26%.
DTC 36 Distributor (Opti) Ignition System - Sets when faulty high resolution pulse or extra low resolution pulse detected. The effect of this code is very minor, causing a slight loss of accuracy in spark timing.
DTC 41 Ignition Control Circuit (Open Circuit) - Sets when the ICM does not receive the pulses from the PCM that tell the ICM to fire the coil. Engine would not run with this code active.
DTC 44 Bank 1 O2 Sensor Circuit (Lean exhaust indicated) - This code cannot set in "Power Enrichment" mode, which is typically where the engine is operating at WOT or close to WOT (depending on RPM). Sets when the O2 sensor indicates less than 200mVolts for 50 seconds.
DTC 48 MAF Sensor Circuit - Sets when the engine is running (PCM detects reference pulses from Opti) but there is no frequency signal from the MAF sensor. Likely an open circuit.
yes the light only comes on after flooring it , under normal driving conditions it won’t however just to get it to the smog place which is about 35 mile round trip here and back it spent half a tank of gas. And no the code immediately clears after turning the car off and turning it back on
1. Are those codes indicated (in the scan device) as "stored" or "active"?
2. Does the SES light comes on ONLY when you put the accel pedal on the floor? Got it
3. Does the SES light go off when you back off on the pedal?
And no the code immediately clears after turning the car off and turning it back on
Are you describing the SES light, or the existence of codes in the PCM? Codes in the PCM should not clear because the key was turned to "OFF". They should remain stored.
1. Are those codes indicated (in the scan device) as "stored" or "active"?
2. Does the SES light comes on ONLY when you put the accel pedal on the floor? Got it
3. Does the SES light go off when you back off on the pedal?
Are you describing the SES light, or the existence of codes in the PCM? Codes in the PCM should not clear because the key was turned to "OFF". They should remain stored.
oh okay I understand now , I only had the codes read after the light was on however , I did not check to see if they were stored or not .
