Still having issues with running rich and lacking power on a 350. Are there any decent shops that know how to work on a TPI setup in Kansas?

 

What all have you checked out on it or done to it? I ended up working on mine after the shop couldn't get it right. Ended up being a combination of things biggest being the timing was so far off.

 

Plugs, wires. Checked spark, fuel pressure at rail and regulator. Timing is good. Fixed fuel return overflowing (vent valve clogged). Injectors have propers ohms and i can feel them firing with a screwdriver.

 

Sorry can't help with a good shop so if my advice gets annoying feel free to say. When you pulled the vacuum line from the fuel regulator no gas smell or anything in the line right, and did it change the fuel pressure? Also have you tried just cleaning the throttle body ad well? I have a pdf of the FSM for an '88 if you want me to email it to you. To big to attach her but can try to email if you want?
BTW I use to do the screedriver trick, then found a light that plugs into the plug at Harbor freight for like $3.99 way easier than trying to ground out a plug wire I'd recommend if you get a chance to get one.

 

i absolutely appreciate the help, ill take any I can get. No gas from the regulator if I recall, I will check again today. It has a new TPS and MAF sensor, the TPS is in the correct position. What plug are you referring to that you used a screwdriver or harbor freight tool? Ill pm you my email

 

The fuel pressure jumps by about 10 PSI when I unplug the vacuum line from the fuel pressure regulator. No fuel coming out of it as far as I can tell. This is with the car running

 

Here is the link on Third Gen from where I downloaded the 1988 service manual. Sorry its slightly over 100 mb so wouldn't let me attach it. Hope it helps you! Emailed you as well.

1988 Firebird Service Manual For Download - Third Generation F-Body Message Boards

 

Thank you! I am downloading it now

 

IIRC pressure is somewhere around 42-45lbs with it disconnected. Maybe someone with more knowledge will chime in or I'll see if I can find it.

 

This might be a good read for you to-
https://www.thirdgen.org/forums/tpi/...sometimes.html

 

10 psi was a bit of a stretch. The fuel pressure is about 37-38 and it jumps to 45 when disconnected. A 7-8 pound increase

 

Weird part about that is mine fires up instantly after running. I dont think its flooding itself after it shuts off, at least not enough to cause a starting issue

 

That seems about right another member said the below and think it seems correct-
Here are my fuel pressures:
At key on while pump is on: 42 PSI.
At key on while pump is off before pressure slowly bleeds off: 40 PSI
Engine at idle: 38 PSI
Engine off idle (probably 1500 to 2000 RPM): jumps to 41 during tip-in and drops quickly to 31 PSI
Engine at idle with vacuum hose removed to simulate WOT with no vacuum: jitters between 42.5 and 43.5
Engine off idle (probably 1500 to 2000 RPM) with vacuum hose removed: 43 PSI steady

 

Bad injector somewhere or how about your O2 sensor.
Sorry misread your screwdriver injector thing earlier was thinking how we use to disconnect a spark plug wire and ground it with a screwdriver.
I know that manual is a long read but is the exact steps a mechanic should follow.

 

No idea on the O2 sensor, at least its not throwing a code. But past that I have no idea. Injectors have good ohms and if I probe them with a skinny metal rod I can feel each one tapping denoting its firing. I do not know if they are the original to the car or have been replaced. Checked the OBD1 again today and still no codes

 

Ill check these tomorrow likely, worst case later in the week depending on work

 

Other stuff to check: base timing with est disconnected, exhaust leaks around o2 sensor. Datalog might be helpful.

 

checked timing earlier, it was good. Will check for exhaust leaks. How do I datalog? I assume plugging something into the ECM and running it to a laptop?

 

To data log you will need a cable, laptop and Tuner Pro Rt free software. Hit up Tuned Performance on this board and I think he has the cable. There is a learning curve to this. You will have to search in the DIY Prom forum and you can find how to's on the set up. You will need a file (mask) that corresponds with your ECM and engine that is loaded into TP RT, I think Tuned Performance has those also. This would be the best way to diagnose your problem. There are a few sensors could be not reading properly and Tuner Pro lets you see the readings of these sensors. For example if the CTS is bad it will send a cold reading to the ECM and cause it to over fuel. If your injectors are not original that could cause a rich running condition also. TP RT will let you see the readings that effect a rich or lean condition (BLM and AFR).

 

Thank you, I just sent him a message.

 

Did you solve it?


Most shops are terrible with OBD1 cars I'd say.......they probably can;t do much more than the above average home mechanic.



Did you smell the little vacuum line that goes to the regulator? Mine smells fine.... / no smell most of the time......but will occasionally smell of gas so i assume its leaking / not up to spec despite the pressure readings being actually the same as yours.... .... yes, i go and smell my lines randomly more than once lol


Also, I heard someone on the TPI Facebook forum replaced their pickup coil and fixed some idle and running rich issues. He did not go into detail though but just said that replacing the distributor solved his rich / idle issues..... as a reply to rich / idle issue question.... (note: I think Tuned Performance also runs the FB page)

"Weird part about that is mine fires up instantly after running. I dont think its flooding itself after it shuts off, at least not enough to cause a starting issue"

I have the same / similar issues...starts fine but I run rich and have a random high idle issue despite no vaccum leaks....... smells so bad that Im literally gassed out / gagging within 5 seconds... and the C02 detector alarm comes on lol


Might want to consider changing the FPR / pickup coil to see if it helps......seeing as its all old anyway and maybe not doing their job properly.


....... im in the process of rebuilding the distributor with all new Pickup / ignition module and also planning to later do the FPR.

 

For what it's worth that FSM I shared has a simple test for the pick up coil just need an ohm meter if I remember correctly. Was about to test mine when I checked the timing. After the mechanic had worked on it the simple fix was adjust the timing that was over 20° off. Of course about 6° BTDC with the EST wire unplugged is where it shoukd be. Think they tried to set it while it was plugged in. I also fixed some vacuum leaks and replaced some old hoses, cleaned the throttle body, pulled a good "BOSCH" MAF(these can be found used on the interwebs still good) from my other GTA and a few other things I'm forgetting. Runs like new again. Know you said you checked the timing but the book calls for 6° BTDC with the EST unplugged and lots of people seem to forget to unplug that and the ECM wants to try and adjust timing and make it run like crap. Also if you take the ignition control module to a parts store they will test it. Ive heard its a good idea to have them test it several times something about it can test okay cold. GL!