I have a 88 camaro with a 305 tbi, and i've recently discovered a strange issue that i can't make sense of. When i drive it, if i suddenly mash the gas to wide open throttle, it'll make less power than my pontiac sunfire. However, if i gradually push the pedal all the way to the floor, it produces a good amount of power. I was just curious if anyone has any idea what may be the culprit behind this. Thanks in advance.

 

is it a automatic or manual? by any chance is it dropping a gear or two when you go WOT. it may be a transmission problem maybe your torque converter.
Joseph

 

o sorry...i guess that would have been a useful fact. Its a 5-speed manual

 

I am having the same issue...except I get a Code 43 with it.

 

Im thinking You are sucking the manifold Dry, when jumping the throttle.. and when you slowly acclerate the fuel /air mixure is steady.

Whens the last time you changed the fuel filter? Dont lie either.

 

Vette, it could be the forced knock test, detonation, or false knock. The ECM adds lots of advance to force detonation to test teh sensor. If it doesnt see any knock, it sets a code 43 and bars all spark advance except at closed throttle.

 

honestly...i haven't changed the fuel filter since i've owned the car. I picked it up mid january this year and the previous owner said he had changed all the fluids and the fuel filter recently. I've since changed the oil...threw some 20 50 in to try to keep oil pressure up a bit. But aside from that all i've done is changed the thermostat and put in a jet fan switch...which by the way works wonders...it does, however, have a open air element and a flowmaster cat back. other than that its stock. Thats about all i can tell you about the car, so again, any help from here is greatly appreciated

 

First and foremost, Marballfire, I am not attempting to hi-jack your thread, just simply trying to gain from it.

Regarding the fuel filter, I changed mine just last month. My Coolant Temperature Sensor (on the front of the manifold) is less then a year old. New knock sensor pigtail in the past few months since my old one was shot. New IAC, soon to be new TPS and new rebuilt TB. Sam as Marball, I have a 3" cat-back, just no open element. Stock chip right now. I have had a Jet Stage II chip in, but same problems occur. Today I disconnected the Knock sensor to see if it did anything while driving around, no difference I can tell. However, in my case, you can see the idle get erratic at times and almost stall out the motor (once in a great while it does stall the motor).

 

Sounds like a sticky EGR valve. If it sticks open, you're idle will be erattic. Mine was causing the car to have the exact same WOT issue as yours. Pulled the EGR vacuum and plugged it. Runs like a champ now.

 

Speaking of the EGR, I checked it out today. I pulled it off and it had build up on it. Couldn't really clean much of it off though. I re-installed the EGR and started up the vehicle. I don't know how the EGR is supposed to work, but I will explain what I seen:

At idle (w/the air cleaner off and the vacumm line plugged that controls the cold start valve in the air ducting and everything else hooked up correcty) I watched the diaphram in the EGR. No movement. There was also no vacuum in the line hooked up to the EGR. So I took the line that runs from the TB to the sensor next to the EGR and ran that directly from the TB to the EGR. Still no movement of the diaphram. So I hooked that vacuum line back up to where it is supposed to be. Then I proceeded to hold the vacuum line that goes to the EGR against my thumb to see if there is any vacuum at all in it. There was none at idle, but as I increased the RPM's the vacuum got stronger. So I hooked that line back up to the EGR and it still didn't move the diaphram. So I figure that means the EGR is F'ed

 

C5
Get a handy vacuum pump and check if EGR valve holds vacuum. EGR's diaphram goes out with age.
//RF

 

Shouldn't the EGR have moved when I hooked up the vacuum line directly from the TB to the EGR and bypassed the sensor (I really do need to learn the name of that sensor)? It should've opened the EGR up and killed the motor right? I know just moving the diapgram around by hand it was just about stalling the motor. I would think with that strong and constant supply of vacuum, it would open the diaphram up and kill the motor. Or at least notive some sort of stumble. However, in my case, there was none.

Furthermore, I noticed some build up on my cap (again). I need to scrape this off still. Probably will help out some. But why do I keep getting build up on my cap? I will sand it off, and it'll come back. Could this be causing my issues with the erratice power? When my car begins to act up, my temperature gauge goes insane. You will see it rise the longer you hold the gas. When you let off the gas, it will slowly drop. Then sometimes it'll go right back to normal.

 

The increase in temp could be due to detonation. Detonation causes an early burn among other things, which can dump alot of heat into the motor.

Also, not all EGRs will open with vacuum alone. On the EGR valve, there should be a 3 digit ID code that IDs what type of EGR it is. Search here on TGO for it. It should come up without too much effort.

Marballfire, if you stomp on the throttle, do you ever get any backfiring out the TBI? It sounds like the engine is either leaning out or going into detonation, or something else is triggering the knock sensor. Also, any mods?

 

Well, I spoke to my cousin today (a BMW mechanic) and he gave me some interesting insight to what he thinks might be the issue. Just the other day I blew the heater hose that connects right next to the distributor. He is thinking that there may have been some sort of hole in the hose before it blew that was causing steam to get inside the distributor cap. Once the steam got inside, it would start causing cross firing and mis-firing. Furthermore, he said that once I turned the engine off, if the radiator cap wasn't allowing air back into the system, then the small hole in the hose might have let air in the system. As a result, it would cause an air bubble. So that pocket of air would become super heated. Whenever it would come across the temperature sending unit it would cause a spike in temperature which is why I seen the spike on my temperature gauge. I have already replaced the hose. He said to take the distributor cap off (or preferable the dstributor as a whole) and ensure it is dry of any water. Furthermore, he mentioned to use WD-40 and some compressed air to ensure any and all liquid is out. Then he said to get the coil tested too to ensure it is working properly.

 

From my experience, its rare to have air become trapped in the system. The engine is lower then the radiator, which means that most or all the air works its way out to the puke bottle. Low coolant, however, will cause the temp to fluctuate randomly.

 

dimented...yes i do get backfiring out of the TB sometimes when i stomp it. I've been too busy lately, but i plan on gettin out the timing light this weekend and seeing where thats at.

 

My cousin also mentioned to me that backfiring out the TB could also be a fuel pump related issue. Luckily I don't have that issue haha...I'd hate to have to replace the pump.