OKay so after changing my plugs, wires, rotor, cap, injectors (bosch3), and fuel pressure regulator( had fuel running through the vac lines!) My car ran great, however, over the past 2 months it has started to screw up again! I am so unsure as to what it can be! First it started to run a lil rich, then it developed a misfire, and now it seems like I am running a stall converter! My oil pressure on the gauge is at 30 or so while idling, and gets to around 60 while under a load. Almost forgot to add that when I took it for a test drive after I put her all back together she ran beautifully, except for the occasional grind from the throw out bearing in the clutch, (waiting for it to all give out to replace or cooler weather here in Arizona) but, when I went for a drive a few days later, ran it in between also, I couldn't get the rpms past 3500, seems to hesitate around 3000. She is still doing this as well. Anyway, any help would be so greatly appreciated, I am somewhat mechanically inclined, so I can do most things, I was able to change my injectors with a write up on here, by myself. Please hellllllppppppp!

 

Oh, and I ad replaced the ignition control module, I'm gonna head to autozone and get a cts, see if that helps in any way! Let's all cross our fingers!, I hate going there because they treat me like crap because I am a female, like we aren't supposed to know about cars! I can't help it, I love cars!

 

So when I went to leave, started her for the first time today, she ran great, oil pressure was at 45. So I decided to take a lil drive and let her heat up a bit. Well of course she did and started to run shitty, also oil pressure gauge(cluster) shows drop in pressure as it heated up got to about a lil over 220 with oil pressure a bit below 30. Hope this helps anyone who may have some type of clue to this mystery. I got the cts, but have to wait to put my kids down for a nap before I get a chance to tear into it! Again, wish me luck!

 

Oil pressure dropped from 60 to 30 while driving??

Can you do a compression check & leak down test?

Check the oil for clues of bearing wear & coolant?

I know this is very 101, but it'll atleast be of some mind-insurance!

 

oil pressure slowly went down as the car temp went up during the drive of about an hour

Compression check is possible but as you know the plugs r a pain to get to.
What is leak down? Checking for leaks?

Oil looks fine, also no loss of water.

 

After changing the cts seems to be better and now she doesn't fall on her face at 3-3500 rpms, which is nice! So at least I can knock that off of my list!

 

Oil pressure is technically a measure of flow, otherwise you would have stuff spewing out of your engine. An oil pressure gauge works by the oil pushing on a spring loaded valve with a resistor that converts the signal electronically. That is why your dash doesn't have a fluid line running to it. Did you change the viscosity of your oil (i.e. 5w-30 to 20W-50)? My engine carries less pressure with 5W-30 as compared to 20W-50. It means the lower viscosity (which is also a measure of flow) exerts less force on the spring in the sensor. But, the 5W-30 flows more than the 20W-50.

So a lower "oil pressure" is actually a reduction in the flow of oil if you haven't changed the viscosity. When an engine warms up, the oil pressure will drop. I have also seen engines in which the oil pressure drops when the oil is old and contaminated and needing to be changed.

So at 30 psi, you are still getting flow, but not as much. I would look for a restriction somewhere (oil filter maybe) or a defective sending unit.

 

One other thing - my 92 305 runs at 30 psi when warm, 50-60 when cold.

 

Okay great thanks for reassuring me! What a relief! Any how, after changing the cts she now seems like she is running on 5 cylinders! WTF! Um, on the driver side all the metal pipes(emission) are really hot while the 3 back ones(FIREWALL) are much cooler! Gonna get around to check compression and spark sometime this week but idk! I swear she is more high maintenance than I am! I am wondering if I will ever get to drive her while she is able to run like a champ!

 

Do determine if you have a legitimate cylinder misfire, start the car. Pull off a plug wire from the spark plug and see if the engine sound changes. Careful, they will bite sometimes.

 

My husband has decided that he doesnt want me to get into it until he has a couple of days off, just in case I screw something up or need some help. So I'm gonna wait and see, IDK maybe while he is at work I can do a few small things! I also noticed that my egr valve has nothing inside of it! Replaced the pcv valve today, needed it badly! Haven't started it yet because I would like it to be cooler when I go to pull stuff off, I'll keep you updated!

 

Please dont pull wires off plugs on your HEI while the engine is running. Your HEI makes about 40KV and will knock a grown man on his butt. Use a cheap adjustable spark tester to look for weak KV on the cylinders that seem to be misfiring. If you really want to perform a cylinder drop test, use a set of spark plug boot pliers with a test lead taped to the metal part of the handle and clipped securely to a good engine ground. You can also use a test light, attached to a good ground, to pierce the wire boot at the cap. I dont prefer this method as it punctures the boot.

Since your ignition tune is new, I doubt that this is an ignition misfire to begin with. Use a stethiscope to listen for injector "click" at the injectors in question. Compare to a good cylinder. Unplug injectors and listen for power drop. Check injector pulse with a test light at disconnected inj connector. One side will be 12v, the other side should flash with the light's clamp connected to batt+

 

Also, check plugs on the cyls in question. Perform a compression test if none of the above tests shows any cause for the misfire. Look carefully for inlet air (vacuum) leaks. Pull the check valve out of the brake booster and plug it with your finger. If the engine smooths out, replace your brake booster. Check fuel pressure.

Btw, oil pressure drops with higher engine temps as the oil thins with heat. This is normal.

 

Im gonna tear the plenum off this am while my hubby is asleep and figure out what EGR I have, considering the current on is just a frame and the diaphragm is non existent! Don't worry I'm not brave enough to do the plug check, I'm usually the one who cranks!

 

I Finally talked my hubby into checking fuel pressure, after changing all these other parts, which needed to be done anyhow. I don't think any type of maintenance was done besides oil changes, unless it was absolutely necessary, joys of buying a used car! I unplugged the tps and let me ses light come on which it did then plugged it back in and it went away. My husband has been thinking my computer is bad. But, since it reacted this way does it mean it's actually good? Ran the correct code also. I'm gonna take a look into the brake booster after I finish the egr if I have time, I have tons of homework to do!

 

"Generally, if you think the ECM is bad, look more closely because you're probably missing something." I heard this a thousand times in GM tech school. Most all the time it proves true. Honestly, out of thousands of computer controlled vehicles I have diagnosed and repaired over 30 years, I have actually replaced less than ten ECMs that were actually the cause of the problem. The hand full of others were "oops". This kind of "oops" gets expensive real quick.

I could scold you for throwing parts at your car's issues, but most of what youve replaced are maintenance items, such as all the tune up parts. The injectors on these cars are such an issue that they should almost be a maintenance item. So, I guess youre doing okay so far. If you think you may have an ECM issue, acquire a suitable scan tool and look at data while you run and drive the car. You will want to familiarize yourself with the various PIDS and their relationship to one another first so you can make sense of what is happening. Watching data will tell you if the ECM is working properly. Chances are its fine.

Perhaps this bit of information will be helpful: The generation of spark is completely covered by the distributor and coil. If you get no spark it is in this system somewhere. The ECM has nothing to do with generating spark, only with managing spark timing when in EST mode. If you are missing spark on a few cylinders, it can only be in the secondary ignition circuit. It is most likely not the coil because, while a weak coil can cause loss of combustion under load, it almost never causes misfire on select cylinders. This leaves cap, rotor, wires and plugs. It is possible that the wires to the cyls in question have been damaged since you replaced them.

The injector drive on the TPI is "batch fire", meaning that the injectors fire in a "batch" every revolution of the crank. The ECM has two drivers. Each driver fires 4 injectors. The "banks" are divided by left and right. It is possible that your injector circuits may be faulty, causing you to lose drive of the 3 injectors in question. Also, quality of replacement injectors varies widely by brand. Bosch is the best. Others get worse from there. However, losing 3 in a group would be too wierd. More likely a defective power or drive circuit. Hope this helps.

 

I can't thank you enough for your help and advice! As far as throwing parts into it, That's not what I have been doing, she has 146,xxx miles and the previous over only put 1000 miles in a year then she sat for 2 years before that. I do not think anyone really took care of her properly! I did use the recommended Bosch 3 injectors 19lbs from South Bay, After I took the plenum off, my hubby woke up and got after me for starting the fix without him. Well he told me to crank the car and he felt that the back manifold(Firewall) on the passenger side is not sucking any air into it. So now he is thinking about tearing further into her and dbl checking the valves and lifters for that area. But this won't be until tomorrow after he wakes up cause he works graves tonight! So for now the plenum is off and in the morning while he is sleeping I'm gonna finish taking it apart so when he gets up he just has to look. (I try to make the job as easy as I can for him, so he actually feels like working on her) Anyway, I will keep you updated, and if you have any other idea as to why it's doing this let me know please! Thanks!

 

Did you check spark before you removed the plenum? You cant check spark when you cant run the engine. You can check injector pulse with the plenum off though. Just be sure to disconnect the coil wire from the dist cap and ground it before cranking the motor. The motor will start with the plenum off and rev like its gonna blow up with nothing to hold it back.

 

Haven't checked spark yet, my hubby has to do that, I know it won't work taken apart. I have had it rev up when I changed my injectors, one of the gaskets tore on re installation, scared the crap outta me! LOL!

 

ok so after a LOOOOOONG day of getting pretty much nowhere! I have been able to figure out that my lifters, valves, rockers are all fine. Car has plenty of spark, just still the tick from under the plenum and still running on 7 cylinders, compression seems fine, haven't checked, but the manifold are sucking in air appropriately. I did notice is that the front driver side(bumper) line is not getting as hot as the rest. IDK! So frustrated!

 

fuel pressure is at 35 pretty consistent, is this normal?

 

after 3 days of opening, testing, and adjusting, I am still coming up empty handed! Idk what to even sat, I know my injectors are clicking quite loud so we were wondering if they tick because they are starved? Heck, idk at this point, wanted to cry all day because I have been so flustered over this car and her many issues! Vac check came back fine, compression all came in around 140.....um plugs are fine wires too.....

 

Day 4, thanks goodnes the weather has cooled down here enough to stand being outside. Anyway, I changed the fuel filter and took off the egr but it was fine. Last minute took off the icm, which was just replaced, and found out it went bad already. Car runs much better now but still has hesitation when taking off no matter the speed, acts like it wants to but is shy. Anyway, we noticed that the plug wires are arching and sometimes traveling up the wire so gonna get some better plugs and wires here pretty soon, I'm gonna go with the 8mm msd wire but need a plug recommendation. Also it seems as if the engine has a cam, but not sure. Is there any way to tell? Thanks!

 

Ended up having 3 clogged injectors, Julie at South Bay hooked me up on replacements faster than I expected!

 

My daughter is a UTI automotive graduate, but after she corrected them several times
They scatter when she comes in.
She said check for gray smoke at the tail pipe before changing the CTS.

 

That's awesome! I wanted to go to school for mechanics and open a female run shop, however, things don't always work out the way you would like sometimes, so it's accounting for me! Anyway, thanks for the advice really appreciate it! I had to put one of the newbies at Autozone in his place the other day, he told me that they are unable to check my icm! I said, "you better ask someone else bcuz I bought it here and was told my last one was bad!" He quickly changed his tune, thank goodness I'm in there all the time so the manager took care of me! So I guess things there are changing!