my 2.8 will surge immediately when I start the car cold in the morning. It will go up and down and eventually go down enough for the engine to stall. The only way I can keep it running is to get on the gas. Once it warms up the problem goes away, but the car still seems a bit sluggish until its been driven for a good while.
The 2.8 has about 3000 miles on it. The sensors are almost all new. I tightened all the ex manifold bolts which were loose before since i never retightened after the initial install. Ignition system is all new. I replaced the IAC with a spare, and the problem persists. I replaced the air filter.
I searched the archives but the threads never end with resolution, so I don't get any useful info.
Any bright ideas anyone? I am really getting frustrated.
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02:33 AM
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FordsNeverDie Member
Posts: 952 From: Puyallup, WA Registered: May 2003
my 2.8 will surge immediately when I start the car cold in the morning. It will go up and down and eventually go down enough for the engine to stall. The only way I can keep it running is to get on the gas. Once it warms up the problem goes away, but the car still seems a bit sluggish until its been driven for a good while.
The 2.8 has about 3000 miles on it. The sensors are almost all new. I tightened all the ex manifold bolts which were loose before since i never retightened after the initial install. Ignition system is all new. I replaced the IAC with a spare, and the problem persists. I replaced the air filter.
I searched the archives but the threads never end with resolution, so I don't get any useful info.
Any bright ideas anyone? I am really getting frustrated.
Honestly, I would cut and paste your post into an email to Anthony @ WCF. <sales@westcoastfiero.com>. He is extremely informative in stuff like this, and if him & Chris can't figure it out, you may wanna throw it away and buy a Ford! ha ha...
--- Goobz!
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03:01 AM
Garethster Member
Posts: 363 From: Duncan, BC Canada Registered: Oct 2002
I'm going to guess you may be seeing a vacuum leak into one cylinder. Possibly around your MAP sensor. Other possibilities: clogged fuel filter (check fuel pressure), slow O2 sensor (but not very likely)
I didn't replace the fuel filter because frankly I just did last year when I installed the first 2.8. I have since installed a new 2.8, that ran fine up until oddly enough I removed the stock rear 1/4 fenders and the intake tube that goes with it. Thats when I started seeing a strange idle. But it wasn't the same problem I am getting now, which I explained above. It seems that nothing works right for very long after I fix it.
The O2 sensor was also replaced last year at the same time. The vacuum leak could be the case I guess, I'll spray some TB cleaner around and look for jumps in the idle. I have had vacuum leaks befoe and they didn't affect the car in this way. I am ready to pull my hair out. Last time I had a vac leak the idle was really high and made the ex manifolds glow. I am getting a major surge on cold start that ends up stalling car. Then the car doesn't respond right away when I hot the gas. Which could be either a vac leak, or a fuel problem. But then when it warms up enough, the idle smooths out and the gas reacts better, but still a little sluggy I think.
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03:05 PM
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avengador1 Member
Posts: 35468 From: Orlando, Florida Registered: Oct 2001
Did you replace the intake tube with one of those CAI tubes, and if so where did you relocate the intake temperature sensor to?
No I didn't actually remove the tube to the airbox, I just removed the stuff from the airbox to the 1/4 fender intake scoop. Since the Aus stage 3's obviously don't use the stock set up. So there shouldn't be any problems there, but it did run a bit different after that oddly enough.
This is the post I made right after swapping fenders. I guess I was having the same problem before. Although it seems that my temp light was screwy as well. The temp light problem was just a bug I think, but the surging is still there.
"My temp gauge doesn't work for some reason (new sensors already). So I depend on my temp dummy light. Yesterday I finally got around to installing my ground effects and Aus stage 3 1/4 panels. I removewd the airbox and am now letting the air come straight into the filter housing. When I started my car up after all of that the temp light came on and stayed on. In addittion to that the car is surging on startup and jerking back and forth if you stay off the gas and coast in 1st or second. But the strangest thing is the car feels like it has another 15 ponies? . I didn't have the elbow piece that goes from the air filter housing to the water seperator/intake scoop before because I didn't have it. It ran fine like that even though it was sucking slightly warm engine air in, so I think that is the reason why the car is faster now, since its all cold air now. But what happened to the temp light and why am I suddenly bucking more than before. Tje car always bucks a little bit in first, but now its completely noticeable. This is a new reman 2.8 with all the usual dressing to make power. "
[This message has been edited by connecticutFIERO (edited 07-27-2004).]
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04:40 PM
avengador1 Member
Posts: 35468 From: Orlando, Florida Registered: Oct 2001
Maybe that sensor itself went bad. I know the one that was in my car was rusty when I bought the car. I replaced all of the sensors in my car when I did the engine swap and everything is working pretty good. (knock on wood)
I just put in a 3.4 PR motor into my GT. It surges and stalls out ONLY in the early morning when I start it for the first time. Itll surge for about a minute or two, usually stalls or needs a blip of the gas pedal to keep it running. After probably 10-15 surge - near stall's, it will suddenly be fine, Idling at 1500. The Idle stays up there till the engine is well above the 100º mark. Other then that its fine. But hopefully when I upgrade the electrical system there will no longer be a problem (Im upgrading to Coilpacks, and a 1227730 computer with a 2 bar map, this is just incase I decide to "pressurize" the intake)
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12:14 AM
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Master Tuner Akimoto Member
Posts: 2267 From: South Florida,USA Registered: Jul 2003
This sounds like a classic case of the coolant temp sensor and what generally happens is the sensor sends a signal to the ECM telling it how much gas to send to the engine on start up and warmup,if this is defective the ECM will get mixed or false information and can cause erratic start up and idling ....try to get a scanner and obtain a code readout and that should pinpoint your problem.
As Master said.. Marcs car was doing something similar. I hooked it up to the scanner, it said the temp was -30º. We can also check the CSI/S. Lemme know. If you're free this evening, I might bring the 'Black Beast' by...
As Master said.. Marcs car was doing something similar. I hooked it up to the scanner, it said the temp was -30º. We can also check the CSI/S. Lemme know. If you're free this evening, I might bring the 'Black Beast' by...
Oh yea, and the white car is just about sold..
What? Sold? Why on gods green earth would you do that? ANd what black beast are you talking about. Fill me in here. I would love to hook this sucker up to a scanner. I would drive your place, but my clutch isn't working right now and I have to fix that now too. Let me know if you can come to my place. It might rain though, so we'll see.
I was gonna go see about helping my uncle with his car, and then we could have taken it for a test drivve to your place, maybe hook up the laptop or something. There are a few sensors to check, althogh new. Also, put your finger over the IAC hole to see if the car stalls, if idle doesn't change much, its a sure sign of a vac leak. It should idle down & Out.
I am having the same prob with my 84 2.5L. I made a post a few weeks ago but got no replies. Looking forward to reading more. What does IAT and IAC stand for?
I am having the same prob with my 84 2.5L. I made a post a few weeks ago but got no replies. Looking forward to reading more. What does IAT and IAC stand for?
Any trouble codes? After checking the codes, disconnect the battery and reconnect it about 5-10 min later to clear all ECM info, let the car cool completely (like overnight), and try starting it up again. If it starts normal, your ECM most likely is learning improper values to adjust the air/fuel ratio, and it's most likely either the o2 sensor or the MAP sensor giving false readings messing things up.
it amazes me how many of our Fiero's have this problem and there is no sure fire solution that I have read or heard of. it must be a combination of factors...
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02:33 PM
Graudefas Member
Posts: 352 From: Sauk City, WI, USA Registered: Jul 2002
Two things... check your ground wire (by the thermostat housing) for continuity... sometimes they rot away and all manner of strange stuff can come about.
Another thing: you mentioned you changed lots of sensors... did you reset the computer?
This sounds like a classic case of the coolant temp sensor and what generally happens is the sensor sends a signal to the ECM telling it how much gas to send to the engine on start up and warmup,if this is defective the ECM will get mixed or false information and can cause erratic start up and idling ....try to get a scanner and obtain a code readout and that should pinpoint your problem.
Yep, I had a post on this awhile back....replacing the sensor fixed mine !! Almost acts similiar to a choke.
[This message has been edited by Zoom88 (edited 07-30-2004).]
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06:53 PM
jetman Member
Posts: 7799 From: Sterling Heights Mich Registered: Dec 2002
Any trouble codes? After checking the codes, disconnect the battery and reconnect it about 5-10 min later to clear all ECM info, let the car cool completely (like overnight), and try starting it up again. If it starts normal, your ECM most likely is learning improper values to adjust the air/fuel ratio, and it's most likely either the o2 sensor or the MAP sensor giving false readings messing things up.
At least this is my understanding of GM EFI.
-Jeff
Disconnected negative ( - ) cable, will test this tomorrow morning and report on results.
EDIT,,,,,,It started and ran very well,,,,,the computer was learning wrong values from one of the sensors,,,,,,,now which one?
[This message has been edited by jetman (edited 07-31-2004).]
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08:53 PM
Jul 31st, 2004
Wesley Member
Posts: 768 From: New Orleans, LA Registered: May 2004
Im also intersted in this one my 85 duke has the same problem I have changed the IAC,TPS,coolant temp sensor,and the o2 sensor and still no changes.....bump
I just installed this engine right before last thanksgiving, all the sensors had been replaced before that. The ground wire is fine, I can add a second to be sure though. Jnco I will be home around 7 tonight I am working right now.
The coolant sensor is fairly new, and I checked for codes. Crazy stuff.
I will start by hooking up Jnco's laptop to see exactly what is off, then start from there.
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10:38 AM
fiero go fast Member
Posts: 1728 From: Royersford, PA Registered: Apr 2002
Wow, I too have been having this problem. Usually doesn't completely stall, but it definitely surges when cold. I've changed my Temp sensor just recently too. Be sure to keep us posted on this. I really would like to get rid of this problem too... so damn annoying.
Connecticut, you said you found a vacuum leak that was causing high idle and glowing manifolds... was this high idle just at startup and then die after the engine was warm? and how red were the manifolds? Could you see them in daylight or only in the dark? Where was the vacuum leak at? I just checked my car for vacuum leaks the other day, didn't is really thorough, but didn't find anything. I have KFG stainless headers and the glow a very very faint red that can only been seen in the dark, and I'm wondering if it's just because the headers are pretty thin walled or if its a vacuum leak... could a bad sensor even cause this? I know my IAC and IAT sensors have never been changed by me... maybe I should do that.
Jncomutt, what program you running on your laptop? Winaldl?
It is you cold start SWITCH located near coolant fill tube....
I have this cold start problem too, I checked the resistance of the coolant temp/ecm sensor and it is within spec. , so I suspect Gary Tucker may be on to something here about the cold start switch, the one with the injector style plug near the filler neck. Can't test that sensor so I wil replace it with a spare and see what happens.
quote
Originally posted by fiero go fast:
.... I have KFG stainless headers and the glow a very very faint red that can only been seen in the dark, and I'm wondering if it's just because the headers are pretty thin walled or if its a vacuum leak... could a bad sensor even cause this? Matt
I have KFG manifolds too and they do glow a faint red that can be seen in darkness, maybe its normal?
I have KFG manifolds too and they do glow a faint red that can be seen in darkness, maybe its normal?
You are probably right, thats also probably one of the reasons they are prone to cracking at the welds.
The vac leak I found was a long time ago when I installed my new 2.8, I forgot to install that huge vac line on the underside of the Throttle Body. Man did those manifolds glow, even the Y pipe was bright red. In the daytime.
ha ha...
1986 SE 350 V8
Thanks Aus! 
