Post by: GTRS Fiero on August 19, 2018, 07:18:37 am
My Fiero runs great, once warmed up, but likes to die on tip-in when cold. Once it's opened up, it runs great. It's just from a stop that I notice the issue.
Post by: GTRS Fiero on August 21, 2018, 10:41:10 pm
My plan is to unplug the ECU for a bit, then let the ECU re-learn. My theory is that it may have learned while there was a vacuum leak at the EGR.
In any case, the RPMs do not increase when I put the transmission in drive, which seems odd.
Once the engine warms up, it runs fine, but when it's cold, it wants to die as soon as I put the teansmission in drive. If I manually open the throttle, I can get going.
Post by: TopNotch on August 21, 2018, 10:53:50 pm
In an injected car, the ECM must command the injectors to give that extra squirt of gas. For some reason, that may not be happening in your car.
Post by: GTRS Fiero on August 21, 2018, 10:59:55 pm
Post by: TopNotch on August 22, 2018, 12:30:39 pm
Post by: Raydar on August 22, 2018, 02:19:43 pm
...
In an injected car, the ECM must command the injectors to give that extra squirt of gas. For some reason, that may not be happening in your car.
That command would mostly be based upon what the TPS is doing. I might suggest adjusting the TPS for a slightly higher voltage. (If you manually move the TPS without opening the throttle, it will cause the engine to speed up, just by adding fuel and timing advance. Try it!)
Timing would be my second guess.
Post by: GTRS Fiero on August 22, 2018, 07:06:25 pm
Have you checked the timing? (Even if it's DIS)
Um, how do you adjust the timing on a DIS setup?
Post by: GTRS Fiero on August 22, 2018, 07:07:58 pm
That command would mostly be based upon what the TPS is doing. I might suggest adjusting the TPS for a slightly higher voltage. (If you manually move the TPS without opening the throttle, it will cause the engine to speed up, just by adding fuel and timing advance. Try it!)
Timing would be my second guess.
Manually move the TPS, as in, with my finger? How would this not move the throttle? Does the TPS add fuel and timing advance?
Post by: Raydar on August 22, 2018, 07:39:08 pm
It's not fastened to the TPS itself, though. You can move it manually, while the throttle remains closed. (Kind of hard to describe.)
The TPS functions like an accelerator pump. Moving the throttle provides an injector "pump shot". I think it also advances the timing just a bit.
I know that when I moved my TPS forward, leaving the throttle closed, as I described, it would speed the engine up, to a point. Nothing dramatic, but enough to notice. If I left it in one position, the engine would return to idle in a second or two.
Post by: GTRS Fiero on August 22, 2018, 08:29:32 pm
It almost seems as if my TCC is causing issues. I just don't know why a hill would trigger such.
Certainly, after 20 minutes, everything should be warm. I went through all the gears.
I should also mention that the temp on my gauge only gets about 1/4 of the way. I suspect this is a gauge or sensor issue.
Post by: GTRS Fiero on August 25, 2018, 09:16:12 am
Post by: GTRS Fiero on August 25, 2018, 07:03:16 pm
Post by: Raydar on August 25, 2018, 08:28:21 pm
I had unplugged the TCC, but there was no change. Since the tank is at 1/4, I wonder if the fuel is running to the front of the tank, and the engine is dying from starvation. Easy enough to check.
You might be on to something. Do you trust your gauge? Most Fieros tend to suck wind at 1/4 tank indicated, unless the sender has been "looked at". It's quite possible that the fuel is running away from the pickup.
Post by: GTRS Fiero on August 25, 2018, 08:44:40 pm
I filled the tank, and there doesn't seem to have been a change. My fuel gauge drops quite a bit, the first 20 miles, but the more empty it gets, the more accurate it seems to be. I'm really only concerned with the empty side being accurate, anyway.
Post by: TopNotch on August 25, 2018, 09:49:28 pm
Um, how do you adjust the timing on a DIS setup?
You can't, but you can replace what's causing it to be off. Have you considered the crank position sensor?
Post by: GTRS Fiero on August 25, 2018, 09:50:47 pm
Post by: TopNotch on August 25, 2018, 09:58:40 pm
Where is it?That depends on whether it's home-made or stock. If its stock, it's on the side of the block. The sensor end of it goes through a hole in the block and is next to the notched ring on the crank.
If it's home-made, there is a notched ring mounted on the crank pulley, and the sensor is there.
Post by: GTRS Fiero on August 25, 2018, 10:02:56 pm
Post by: TopNotch on August 25, 2018, 10:18:27 pm
Post by: GTRS Fiero on August 25, 2018, 10:24:36 pm
Post by: GTRS Fiero on August 26, 2018, 09:31:36 am
Post by: TopNotch on August 26, 2018, 11:48:37 am
Unplug each one (one at a time), and see which one the engine won't run without.
Post by: Fierofool on August 26, 2018, 01:26:12 pm
Post by: GTRS Fiero on August 26, 2018, 01:27:55 pm
Post by: Fierofool on August 26, 2018, 01:50:27 pm
Post by: GTRS Fiero on August 26, 2018, 02:10:27 pm
Post by: GTRS Fiero on August 26, 2018, 04:41:58 pm
Post by: GTRS Fiero on August 27, 2018, 09:30:34 pm
After installing the new sensor, I went for a drive. True, it was warmed up by the time I got it on the road, but I went down that hill twice with no issues. It didn't even try to die. I did not take any precautionary measures to prevent it from dying.
I'll play with it more tomorrow, but it semed to have a better idle. I may still replace the IAC.
The bad news is that the new sensor is BWD brand. No idea what the previous 2-year-old one was, but a different brand..
Post by: GTRS Fiero on August 28, 2018, 10:26:07 pm
Post by: GTRS Fiero on August 29, 2018, 08:08:12 pm
I can get a pliers on the O2 sensor, but have no space to move the pliers.
Post by: GTRS Fiero on August 29, 2018, 09:59:12 pm
The tip was covered in carbon. I used throttle-body cleaner to clean the IAC passage, then cleaned up with a paper towel that I had used to catch anything that didn't stay in the passage. I'm not sure about the carbon, or how it got there, but surely the spring shouldn't be like that.
I can probably fix the spring, but I want to see if the IAC is bad or not.
Post by: TopNotch on August 30, 2018, 10:52:08 am
Post by: Fierofool on August 30, 2018, 11:45:59 am
There are two style IAC's. It relates to the pintle shaft. One is smooth round and the other has 2 grooves running the length of it. Adjustment procedure is different for each, but both should have an initial adjusted length from the tip to the gasket flange of 1 1/8 inch.
To adjust the smooth shaft valve, hold the body in the palm of your cupped hand. Using the fingers of that hand, pull the spring out of the notches in the pintle and screw the pintle toward the valve body until you have the correct length. Be sure to locate the spring back into th notches on the back of the pintle head.
To adjust the grooved shaft valve, hold the body in one hand and using your fingers of the other hand, press on the tip of the pintle and rock it side to side. It will slowly move into the valve body until you have the desired length.
If you go a little too far, don't worry. It will adjust itself. A problem and damage can occur is when you don't retract it far enough into the valve body.
Post by: Raydar on August 30, 2018, 04:49:06 pm
Once you reinstall the IAC, take the car for a drive. Let the engine get warmed up, and drive over 30-35 MPH.
I understand that is supposed to reset the IAC to spec.
Post by: GTRS Fiero on August 30, 2018, 07:39:29 pm
Get a new one. That one is toast.
More questions than answers.:
How/why did that happen?
Is this expected of an IAC that has about 2K miles on it, and was new 2 years ago?
Is that IAC unrepairable?
Post by: GTRS Fiero on August 30, 2018, 07:43:55 pm
Retain the gasket. Many new IACd's don't come with a new gasket.
There are two style IAC's. It relates to the pintle shaft. One is smooth round and the other has 2 grooves running the length of it. Adjustment procedure is different for each, but both should have an initial adjusted length from the tip to the gasket flange of 1 1/8 inch.
To adjust the smooth shaft valve, hold the body in the palm of your cupped hand. Using the fingers of that hand, pull the spring out of the notches in the pintle and screw the pintle toward the valve body until you have the correct length. Be sure to locate the spring back into th notches on the back of the pintle head.
To adjust the grooved shaft valve, hold the body in one hand and using your fingers of the other hand, press on the tip of the pintle and rock it side to side. It will slowly move into the valve body until you have the desired length.
If you go a little too far, don't worry. It will adjust itself. A problem and damage can occur is when you don't retract it far enough into the valve body.
Um, gasket? There was green stuff on the threads. I did not do any of those things; i just put the new one in, and went for a drive. I drove around the subdivision, but probably did not get over 35.
How much damage did I do?
Post by: Fierofool on August 30, 2018, 09:02:39 pm
As for what appeared to be carbon on the pintle and in the port, the air for the IAC is from the engine. Without going out and looking at a spare throttle body, I believe it comes from the lower intake manifold via the large hose at the lower back side of the throttle body.
Post by: GTRS Fiero on August 31, 2018, 09:12:57 pm
The new chip from sinister is in.......and........IT'S PERFECT! No more hunting, throttle is fast, smooth, and predictable. I only had a couple hiccups where the p.o. of the harness i bought had spliced the fuel pump circuit monitor wire to ignition. The 7730 didn't like that. So i wired it correctly to the fuel pump command wire and its happy now. The other was that there was no original prom installed on the moates adapter to accommodate limp mode. I placed the sinister chip that came with the ecm in that spot and installed my new sinister chip in the main spot.
No codes, runs smooth. If you let out the clutch a little, it will nudge the throttle up to accommodate the load. You can do this pretty quickly, like in a backing situation, and it won't let the motor die. I'm impressed.
I have to say that my favorite part is startup, just a small flare and then settles down.
Even highway running is smoother. Very nice.
Ron
The little throttle nudge may be a function of the automatic transmission programming.
So, now, are you ready to do your first for-somebody-else conversion?
I'm looking for more clarification on these posts. Is the idle supposed to increase on an auto when shifted into gear?
Post by: TopNotch on August 31, 2018, 11:04:51 pm