CRuby

iTrader: (1)

1st Problem: CEL comes on when starting car and it's hot outside. Afternoon summertime in Fl, 92 degF. Car is cold, ie. hasn't been used all day or night, but it's been soaking up heat in the summer sun. Difficult to start & when it does, it won't idle. After ~ 5 tries it starts & idles OK (sometimes), with CEL still on. Slow rev'ing in park, it tachs up to 4Krpm smoothly, but if I punch it (accelerate quickly) it chokes & sometimes stalls. The odd thing is it starts OK if we try it in the morning after a somewhat cooler (80F) night. But any starting when it's hot out results in above problem.
2nd Problem: CEL not giving any useful codes. I jump TE1 & E1 on diagnostic port & all I get is a continuously blinking CEL & O/D light. It doesn't pause at all to indicate any digits 1-9. Even when I reset CEL via removing neg battery terminal the situation repeats itself. I tried using either diagostic ports under dash & in engine bay with no change.

So, car's in my garage again to fix other stuff (speedo, leaking tailight, etc.)but this one has me stumped so far. I'll try cleaning MAF sensor to see if that changes anything.
Has anyone else encounter this starting sensitivity to hot outside temperature & problem reading CEL codes?
Is the continuously blinking CEL, when attempting to pull codes, a sure sign that my ECU is bad or going bad?
Does CEL continuously blink when there are no stored codes?
CRuby

93MSB

iTrader: (8)

that doesnt really sound like an electrical/sensor issue. If theres something wrong with the MAF it should throw a code. The constant blinking of the check engine and O/D means it hasnt thrown any codes.

have you looked over your vaccum lines? thats what it sounds like to me.

i had an ECU go bad on me and i couldnt get the check engine to flash at all, your ecu should be fine

CRuby

iTrader: (1)

Status.
The easy stuff is done. Fixed leaking taillight by disassembling & re-sealing it. Got used cluster from Aliga & I'm waiting to get car running again before getting new needles & lights.

The hard part is getting the car running correctly. (isn't it always).
I checked for vac leaks using the starter fluid method. No evident leaks. Changed each vac line 1 by 1 because they were old. Still no vac leak.
Cleaned & replaced bearings in IACV & it tests good.
Replaced ECT.
Good Resistance tests on L&R cam position sensors, crank position sensor, TPS, L&R coils, & MAF sensor.
Already had the fuel ECU 12V mod.
Fuel pump & filter changed ~6 months ago.
Plugs, wires, Dist. caps, rotor, Timing belt, H2O pump & tensioners, etc changed ~ 6 months ago.

Started car several times & got to good smooth idle. In park & neutral, I can rev slowly or radpidly to past 4K rpm without any problems, multiple times. Go for my test drive last night & the car bogs down with amost no power. I'm lucky if I got it past 5mph (although I'm guessing at the speed since I didn't change the speedo motor yet). I plan to do more checks this week as I get home from work.

I'm looking for some input as to what might be the cause for good smooth revving when not in gear but little power when in gear?

CRuby

iTrader: (1)

So I rechecked all the hoses & connectors & they look OK. Starts on 1st try & revs so-so in park. A little hesitation & seems like it's missing when rapid throttling. Test drive & is runs very poorly. So I decided to disconnect the MAF sensor. Revs much better & I can finally chirp the tires again. So I think my MAF sensor is the problem. I've seen some posts on cleaning them but where & how? I want to try cleaning before biting the bullet & getting a new one. Here's a picture of the MAF sensor & it's pretty clean on the exterior surface, so what is it that might need cleaning?
CRuby

CRuby

iTrader: (1)

Found cleaning instructions for this Karman Vortex MAF sensor on post#23 https://www.clublexus.com/forums/per...rywhere-2.html

93MSB

iTrader: (8)

so you did the resistance test on the MAF?

CRuby

iTrader: (1)

Yes that's the resistance test I did. Got ~1.1K ohms @ ~85F. The saga continues. I cleaned the sensor yesterday or at least went thru the motions. It wasn't really dirty as far as I could tell. Installed it this morning on the car & connected the MAF plug. Started & drove fine. Couldn't tell anything was wrong. So I thought, OK I must have cleaned it enough to make it work again. Parked the car outside in the sun all day, come home from work & test drive again. Started 1st try but same hesitation & slight miss firing sound when revved in park. Put it in drive & even giving a little gas (not punching it) it runs like a pig. The engine won't rev & I was barely able to put-put out the driveway. Disconnected the MAF sensor & now no change. Still crappy. This thing has me puzzled but I'll keep trying.

CRuby

iTrader: (1)

Oh I forgot to mention. I disconnected battery to clear CEL. On starting, CEL came back on again, & that's when I took the test drive & back. Shut car off & jumped TE1-E1 to attempt to pull codes. Turn key to on, & CEL just sits there glowing. No blinking at all, just continuous light. This is different from prior times I tried checking codes. Then (see my 1st thread) it would continuously blink & never pause. Now it doesn't even blink. I hate to start blindly buying & changing various electronic parts until I know which ones the problem. All test & repair advice welcome.

Ali SC3

iTrader: (10)

try another ECU, you have the symptoms of a bad maf or a bad ecu.
since you checked the maf and you can't even pull the codes, the ecu sounds suspect.

CRuby

iTrader: (1)

Yes, I've been thinking it could be the ECU, but don't have a definitive test to point to that being the problem.
OK, a couple of quick ECU questions:
1) Anyone know what year ECU is OK for my car. '92 SC400 1UZ-FE w/ AT?
I think it's 92-94, but I need to search again.
2) Is SC300 ECU usable on the SC400? (probably a dumb question).
3) Is ~18 years roughly the lifespan for theses ECUs? If I buy another used one, how do I know it doesn't already have the same problem.
4) Are there lots of folks running 92 SC400's with the original ECU?

CRuby

iTrader: (1)

Update: Brought car into garage after it sitting outside in the sun & daily rain shower. In S.Fl. we commonly get a daily downpour in afternoon this time of year. It started but ran like crap, as it has been doing when it's been sitting in the heat. I pulled up passenge side carpet & was welcomed by a soaking wet carpet. Last time I pulled carpet up (~Feb.'10) it was wet too, but it seemed to be from antifreeze as I think the heater core had a leak & previous owner had cut hoses & bypassed it but didn't bother to clean up the mess. Smelled sweet inside! This time around I noticed the bottom carpet region of the door panel was wet too. Driver's side has same symptoms. Add fixing more leaks to the list. I had both door panels off before to patch numerous cracks. Should have checked for leaks then.
The ECU region has a plastic cover which helped keep it dry. I didn't notice any moisture around the ECU wires. By the way what's the other unit for, transmission? After about an hour in the garage with a fan blowing on ECU & wet carpet, I started the car & it ran good. This may be as good a test as I can expect to convince me the ECU might be the cause of the intermitent poor operation. Whatever's going on with it, seems to be sensitive to the ambient temperature. Too hot (sitting in sun all day) & it runs like crap. Not too hot (in morning or overnight in garage) & it runs fine.
AliSC3, +1 more for you. Now I'm definitely convinced.
Anyone care to give some experienced answers to my ECU questions in prior posting?
I have some feelers out for good ECU & MAF sensors (probably good to have a spare?)
PM me if you have one in "good working condition" & preferrably at a reasonable price.
CRuby

Ali SC3

iTrader: (10)

yikes, looks like someone has some cleaning to do. I wonder how how high the water pools in that area while its raining, maybe then it could have gotten the ecu wet. normally it has to do with some components going bad inside the ecu due to age or wear, in this case probably age and possibly some water, the fact that it runs means it isn't completely shorted out.

you could try and replace with another sc400 ecu, the newest year that works for your car would be ideal im not sure the year range since its a 400 and no the 300 wont work.
check the classifieds you can usually find a ecu from some members or even the vendors.
the other option would be to repair your ecu, but since you have possible water damage It may be easier to find another one. you could try opening it up and letting the board dry out completely, check all the capacitors and replace anything that looks faulty.

CRuby

iTrader: (1)

Although the carpet foam backing was completely soaked, there was no standing water above the level of the carpet surface. When I pulled up the floor mat I could feel the carpet was slightly moist but the foam below soaked up most of it like a sponge. A big wet sponge.
I got my new-used ECU & hold it as backup until leak issue is fixed.

So now my ECU posting is morphing into a door leak posting. I removed the interior door panel & sprayed outside the door with hose. With window up, the water runs down the window & past ~.1" wide gap between window & outside seal. Then it's inside the door & gets all over the plastic & leaks out the bottom & onto carpet. I've checked bottom door drains & they're clear. Some of the water was never getting to them as it found another path, into the car.
So I think I have 2 repairs to address:
1) Replace or adjust rubber seal @ outside window sill to close gap & improve sealing.
2) Replace filmsy plastic covering on door & reseal COMPLETELY.

I expect this is another common problem, & I'll do more searching.
But, have other members had, & fixed the same issues. Especially #1 above. Does this seal warp & loosen over time? Do I need to buy new seals or can I tweak the base of them over closer to the window?

CRuby

iTrader: (1)

Update: I fixed the >.1" gap on passenger side between window & outer seal by wedging 9/64 screening spline in the seal groove. This helped push the suedo-seal surface closer toward window and reduce the quantity of water that gets by the seal. Possibly new seals may have reduced the gap, but I think this will work for now. I realize this joint is not intended to be leak-proof since water can still enter on the corner gaps. That's why there is the plastic cover on the inside surface of the door, to prevent water that leaks past the seal from leaking into the interior. Mine was just letting lots of water in at the window seal because of the big gap. Also the plastic sheet wasn't sealed well along the bottom & water leaked past along base of door & onto carpet.

Leak test (or hopefully no-leak test) tomorrow after sealant dries. I couldn't find the black sticky stuff so I used RTV & metal a/c duct tape with trimmed plastic tarp. Also resealed behind speaker.

Swapped in new-used ECU. Car starts & runs fine. Haven't done the soak in the sun test yet though. That's where I hope this new ECU solves the problem. But now CEL comes on and I am finally able to pull a code from it. Could never get codes with my prior ECU. Code is 71, EGR. I've seen the postings about completely deleting the EGR system. Maybe I'll get there, but for now I need to confirm I fixed the passenger side leak & then move to drivers side leak. Then the heat soak test. Door lock cycling is also on the list, but it hasn't occurred yet since the new ECU installed. Don't know if that cured the lock cycling or it's just another intermittent problem.

1JZPWRD

iTrader: (59)

It sounds like you have had your hands full. Once this is done, which. I think it will be, you should be good to go. The ecu are a very common problem on these SC's. Glad you got the little things fixed. Keep us posted on the rest of the symptoms and troubleshooting.